23 Studies on Low-Carb and Low-Fat Diets – Time to Retire The Fad

Young Woman Staring at a Plate of VegetablesFew things have been debated as much as “carbohydrates vs fat.”

Some believe that increased fat in the diet is a leading cause of all kinds of health problems, especially heart disease.

This is the position maintained by most mainstream health organizations.

These organizations generally recommend that people restrict dietary fat to less than 30% of total calories (a low-fat diet).

However… in the past 11 years, an increasing number of studies have been challenging the low-fat dietary approach.

Many health professionals now believe that a low-carb diet (higher in fat and protein) is a much better option to treat obesity and other chronic, Western diseases.

In this article, I have analyzed the data from 23 of these studies comparing low-carb and low-fat diets.

All of the studies are randomized controlled trials, the gold standard of science. All are published in respected, peer-reviewed journals.

The Studies

Most of the studies are being conducted on people with health problems, including overweight/obesity, type II diabetes and metabolic syndrome.

Keep in mind that these are the biggest health problems in the world.

The main outcomes measured are usually weight loss, as well as common risk factors like Total Cholesterol, LDL Cholesterol, HDL Cholesterol, Triglycerides and Blood Sugar levels.

1.Foster GD, et al. A randomized trial of a low-carbohydrate diet for obesity. New England Journal of Medicine, 2003.

Details: 63 individuals were randomized to either a low-fat diet group, or a low-carb diet group. The low-fat group was calorie restricted. This study went on for 12 months.

Weight Loss: The low-carb group lost more weight, 7.3% of total body weight, compared to the low-fat group, which lost 4.5%. The difference was statistically significant at 3 and 6 months, but not 12 months.

Foster, et al. 2003.

Conclusion: There was more weight loss in the low-carb group, significant at 3 and 6 months, but not 12. The low-carb group had greater improvements in blood triglycerides and HDL, but other biomarkers were similar between groups.

2. Samaha FF, et al. A low-carbohydrate as compared with a low-fat diet in severe obesity. New England Journal of Medicine, 2003.

Details: 132 individuals with severe obesity (mean BMI of 43) were randomized to either a low-fat or a low-carb diet. Many of the subjects had metabolic syndrome or type II diabetes. The low-fat dieters were calorie restricted. Study duration was 6 months.

Weight Loss: The low-carb group lost an average of 5.8 kg (12.8 lbs) while the low-fat group lost only 1.9 kg (4.2 lbs). The difference was statistically significant.

Samaha, et al. 2003.

Conclusion: The low-carb group lost significantly more weight (about 3 times as much). There was also a statistically significant difference in several biomarkers:

  • Triglycerides went down by 38 mg/dL in the LC group, compared to 7 mg/dL in the LF group.
  • Insulin sensitivity improved on LC, got slightly worse on LF.
  • Fasting blood glucose levels went down by 26 mg/dL in the LC group, only 5 mg/dL in the LF group.
  • Insulin levels went down by 27% in the LC group, but increased slightly in the LF group.

Overall, the low-carb diet had significantly more beneficial effects on weight and key biomarkers in this group of severely obese individuals.

3. Sondike SB, et al. Effects of a low-carbohydrate diet on weight loss and cardiovascular risk factor in overweight adolescents. The Journal of Pediatrics, 2003.

Details: 30 overweight adolescents were randomized to two groups, a low-carb diet group and a low-fat diet group. This study went on for 12 weeks. Neither group was instructed to restrict calories.

Weight Loss: The low-carb group lost 9.9 kg (21.8 lbs), while the low-fat group lost 4.1 kg (9 lbs). The difference was statistically significant.

Sondike, et al. 2003.

Conclusion: The low-carb group lost significantly more (2.3 times as much) weight and had significant decreases in Triglycerides and Non-HDL cholesterol. Total and LDL cholesterol decreased in the low-fat group only.

4. Brehm BJ, et al. A randomized trial comparing a very low carbohydrate diet and a calorie-restricted low fat diet on body weight and cardiovascular risk factors in healthy women. The Journal of Clinical Endocrinology & Metabolism, 2003.

Details: 53 healthy but obese females were randomized to either a low-fat diet, or a low-carb diet. Low-fat group was calorie restricted. The study went on for 6 months.

Weight Loss: The women in the low-carb group lost an average og 8.5 kg (18.7 lbs), while the low-fat group lost an average of 3.9 kg (8.6 lbs). The difference was statistically significant at 6 months.

Weight Loss Graph, Low Carb vs Low Fat

Conclusion: The low-carb group lost more weight (2.2 times as much) and had significant reductions in blood triglycerides. HDL improved slightly in both groups.

5. Aude YW, et al. The national cholesterol education program diet vs a diet lower in carbohydrates and higher in protein and monounsaturated fat. Archives of Internal Medicine, 2004.

Details: 60 overweight individuals were randomized to a low-carb diet high in monounsaturated fat, or a low-fat diet based on the National Cholesterol Education Program (NCEP).

Both groups were calorie restricted and the study went on for 12 weeks.

Weight Loss: The low-carb group lost an average of 6.2 kg (13.6 lbs), while the low-fat group lost 3.4 kg (7.5 lbs). The difference was statistically significant.

Conclusion: The low-carb group lost 1.8 times as much weight. There were also several changes in biomarkers that are worth noting:

  • Waist-to-hip ratio is a marker for abdominal fat. This marker improved slightly in the LC group, not in the LF group.
  • Total cholesterol improved in both groups.
  • Triglycerides went down by 42 mg/dL in the LC group, compared to 15.3 mg/dL in the LF group.
  • LDL particle size increased by 4.8 nm and percentage of small, dense LDL decreased by 6.1% in the LC group, while there was no significant difference in the LF group.

Overall, the low-carb group lost more weight and had much greater improvements in several important risk factors for cardiovascular disease.

6. Yancy WS Jr, et al. A low-carbohydrate, ketogenic diet versus a low-fat diet to treat obesity and hyperlipidemia. Annals of Internal Medicine, 2004.

Details: 120 overweight individuals with elevated blood lipids were randomized to a low-carb or a low-fat diet. The low-fat group was calorie restricted. Study went on for 24 weeks.

Weight Loss: The low-carb group lost 9.4 kg (20.7 lbs) of their total body weight, compared to 4.8 kg (10.6 lbs) in the low-fat group.

Yancy, et al. 2004.

Conclusion: The low-carb group lost significantly more weight and had greater improvements in blood triglycerides and HDL cholesterol.

7. JS Volek, et al. Comparison of energy-restricted very low-carbohydrate and low-fat diets on weight loss and body composition in overweight men and women. Nutrition & Metabolism (London), 2004.

Details: A randomized, crossover trial with 28 overweight/obese individuals. Study went on for 30 days (for women) and 50 days (for men) on each diet, that is a very low-carb diet and a low-fat diet. Both diets were calorie restricted.

Weight Loss: The low-carb group lost significantly more weight, especially the men. This was despite the fact that they ended up eating more calories than the low-fat group.

Volek, et al. 2004.

Conclusion: The low-carb group lost more weight. The men on the low-carb diet lost three times as much abdominal fat as the men on the low-fat diet.

8. Meckling KA, et al. Comparison of a low-fat diet to a low-carbohydrate diet on weight loss, body composition, and risk factors for diabetes and cardiovascular disease in free-living, overweight men and women. The Journal of Clinical Endocrinology & Metabolism, 2004.

Details: 40 overweight individuals were randomized to a low-carb and a low-fat diet for 10 weeks. The calories were matched between groups.

Weight Loss: The low-carb group lost 7.0 kg (15.4 lbs) and the low-fat group lost 6.8 kg (14.9 lbs). The difference was not statistically significant.

Conclusion: Both groups lost a similar amount of weight.

A few other notable differences in biomarkers:

  • Blood pressure decreased in both groups, both systolic and diastolic.
  • Total and LDL cholesterol decreased in the LF group only.
  • Triglycerides decreased in both groups.
  • HDL cholesterol went up in the LC group, but decreased in the LF group.
  • Blood sugar went down in both groups, but only the LC group had decreases in insulin levels, indicating improved insulin sensitivity.

9. Nickols-Richardson SM, et al. Perceived hunger is lower and weight loss is greater in overweight premenopausal women consuming a low-carbohydrate/high-protein vs high-carbohydrate/low-fat diet. Journal of the American Dietetic Association, 2005.

Details: 28 overweight premenopausal women consumed either a low-carb or a low-fat diet for 6 weeks. The low-fat group was calorie restricted.

Weight Loss: The women in the low-carb group lost 6.4 kg (14.1 lbs) compared to the low-fat group, which lost 4.2 kg (9.3 lbs). The results were statistically significant.

Conclusion: The low-carb diet caused significantly more weight loss and reduced hunger compared to the low-fat diet.

10. Daly ME, et al. Short-term effects of severe dietary carbohydrate-restriction advice in Type 2 diabetes. Diabetic Medicine, 2006.

Details: 102 patients with Type 2 diabetes were randomized to a low-carb or a low-fat diet for 3 months. The low-fat group was instructed to reduce portion sizes.

Weight Loss: The low-carb group lost 3.55 kg (7.8 lbs), while the low-fat group lost only 0.92 kg (2 lbs). The difference was statistically significant.

Conclusion: The low-carb group lost more weight and had greater improvements in the Total cholesterol/HDL ratio. There was no difference in triglycerides, blood pressure or HbA1c (a marker for blood sugar levels) between groups.

11. McClernon FJ, et al. The effects of a low-carbohydrate ketogenic diet and a low-fat diet on mood, hunger, and other self-reported symptoms. Obesity (Silver Spring), 2007.

Details: 119 overweight individuals were randomized to a low-carb, ketogenic diet or a calorie restricted low-fat diet for 6 months.

Weight Loss: The low-carb group lost 12.9 kg (28.4 lbs), while the low-fat group lost only 6.7 kg (14.7 lbs).

Conclusion: The low-carb group lost almost twice the weight and experienced less hunger.

12. Gardner CD, et al. Comparison of the Atkins, Zone, Ornish, and LEARN diets for change in weight and related risk factors among overweight premenopausal women: the A TO Z Weight Loss Study. The Journal of The American Medical Association, 2007.

Details: 311 overweight/obese premenopausal women were randomized to 4 diets: A low-carb Atkins diet, a low-fat vegetarian Ornish diet, the Zone diet and the LEARN diet. Zone and LEARN were calorie restricted.

Weight Loss: The Atkins group lost the most weight at 12 months (4.7 kg – 10.3 lbs) compared to Ornish (2.2 kg – 4.9 lbs), Zone (1.6 kg – 3.5 lbs) and LEARN (2.6 kg – 5.7 lbs). However, the difference was not statistically significant at 12 months.

A to Z Study Weight Loss Graph

Conclusion: The Atkins group lost the most weight, although the difference was not statistically significant. The Atkins group had the greatest improvements in blood pressure, triglycerides and HDL. LEARN and Ornish (low-fat) had decreases in LDL at 2 months, but then the effects diminished.

This study was covered in detail here.

13. Halyburton AK, et al. Low- and high-carbohydrate weight-loss diets have similar effects on mood but not cognitive performance. American Journal of Clinical Nutrition, 2007.

Details: 93 overweight/obese individuals were randomized to either a low-carb, high-fat diet or a low-fat, high-carb diet for 8 weeks. Both groups were calorie restricted.

Weight Loss: The low-carb group lost 7.8 kg (17.2 lbs), while the low-fat group lost 6.4 kg (14.1 lbs). The difference was statistically significant.

Halyburton, et al. 2007.

Conclusion: The low-carb group lost more weight. Both groups had similar improvements in mood, but speed of processing (a measure of cognitive performance) improved further on the low-fat diet.

14. Dyson PA, et al. A low-carbohydrate diet is more effective in reducing body weight than healthy eating in both diabetic and non-diabetic subjects. Diabetic Medicine, 2007.

Details: 13 diabetic and 13 non-diabetic individuals were randomized to a low-carb diet or a “healthy eating” diet that followed the Diabetes UK recommendations (a calorie restricted, low-fat diet). Study went on for 3 months.

Weight Loss: The low-carb group lost 6.9 kg (15.2 lbs), compared to 2.1 kg (4.6 lbs) in the low-fat group.

Dyson, et al. 2007.

Conclusion: The low-carb group lost more weight (about 3 times as much). There was no difference in any other marker between groups.

15. Westman EC, et al. The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutrion & Metabolism (London), 2008.

Details: 84 individuals with obesity and type 2 diabetes were randomized to a low-carb, ketogenic diet or a calorie restricted low-glycemic diet. The study went on for 24 weeks.

Weight Loss: The low-carb group lost more weight (11.1 kg – 24.4 lbs) compared to the low-glycemic group (6.9 kg – 15.2 lbs).

Conclusion: The low-carb group lost significantly more weight than the low-glycemic group. There were several other important differences:

  • Hemoglobin A1c went down by 1.5% in the LC group, compared to 0.5% in the low-glycemic group.
  • HDL cholesterol increased in the LC group only, by 5.6 mg/dL.
  • Diabetes medications were either reduced or eliminated in 95.2% of the LC group, compared to 62% in the low-glycemic group.
  • Many other health markers like blood pressure and triglycerides improved in both groups, but the difference between groups was not statistically significant.

16. Shai I, et al. Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. New England Journal of Medicine, 2008.

Details: 322 obese individuals were randomized to three diets: a low-carb diet, a calorie restricted low-fat diet and a calorie restricted Mediterranean diet. Study went on for 2 years.

Weight Loss: The low-carb group lost 4.7 kg (10.4 lbs), the low-fat group lost 2.9 kg (6.4 lbs) and the Mediterranean diet group lost 4.4 kg (9.7 lbs).

Shai, et al. 2008.

Conclusion: The low-carb group lost more weight than the low-fat group and had greater improvements in HDL cholesterol and triglycerides.

17. Keogh JB, et al. Effects of weight loss from a very-low-carbohydrate diet on endothelial function and markers of cardiovascular disease risk in subjects with abdominal obesity. American Journal of Clinical Nutrition, 2008.

Details: 107 individuals with abdominal obesity were randomized to a low-carb or a low-fat diet. Both groups were calorie restricted and the study went on for 8 weeks.

Weight Loss: The low-carb group lost 7.9% of body weight, compared to the low-fat group which lost 6.5% of body weight.

Conclusion: The low-carb group lost more weight and there was no difference between groups on Flow Mediated Dilation or any other markers of the function of the endothelium (the lining of blood vessels). There was also no difference in common risk factors between groups.

18. Tay J, et al. Metabolic effects of weight loss on a very-low-carbohydrate diet compared with an isocaloric high-carbohydrate diet in abdominally obese subjects. Journal of The American College of Cardiology, 2008.

Details: 88 individuals with abdominal obesity were randomized to a very low-carb or a low-fat diet for 24 weeks. Both diets were calorie restricted.

Weight Loss: The low-carb group lost an average of 11.9 kg (26.2 lbs), while the low-fat group lost 10.1 kg (22.3 lbs). However, the difference was not statistically significant.

Tay, et al. 2008.

Conclusion: The low-carb group lost more weight. Triglycerides, HDL, C-Reactive Protein, Insulin, Insulin Sensitivity and Blood Pressure improved in both groups. Total and LDL cholesterol improved in the low-fat group only.

19. Volek JS, et al. Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet. Lipids, 2009.

Details: 40 subjects with elevated risk factors for cardiovascular disease were randomized to a low-carb or a low-fat diet for 12 weeks. Both groups were calorie restricted.

Weight Loss: The low-carb group lost 10.1 kg (22.3), while the low-fat group lost 5.2 kg (11.5 lbs).

Conclusion: The low-carb group lost almost twice the amount of weight as the low-fat group, despite eating the same amount of calories.

This study is particularly interesting because it matched calories between groups and measured so-called “advanced” lipid markers. Several things are worth noting:

  • Triglycerides went down by 107 mg/dL on LC, but 36 mg/dL on the LF diet.
  • HDL cholesterol increased by 4 mg/dL on LC, but went down by 1 mg/dL on LF.
  • Apolipoprotein B went down by 11 points on LC, but only 2 points on LF.
  • LDL size increased on LC, but stayed the same on LF.
  • On the LC diet, the LDL particles partly shifted from small to large (good), while they partly shifted from large to small on LF (bad).

20. Brinkworth GD, et al. Long-term effects of a very-low-carbohydrate weight loss diet compared with an isocaloric low-fat diet after 12 months. American Journal of Clinical Nutrition, 2009.

Details: 118 individuals with abdominal obesity were randomized to a low-carb or a low-fat diet for 1 year. Both diets were calorie restricted.

Weight Loss: The low-carb group lost 14.5 kg (32 lbs), while the low-fat group lost 11.5 kg (25.3 lbs) but the difference was not statistically significant.

Brinkworth, et al. 2009.

Conclusion: The low-carb group had greater decreases in triglycerides and greater increases in both HDL and LDL cholesterol, compared to the low-fat group.

21. Hernandez, et al. Lack of suppression of circulating free fatty acids and hypercholesterolemia during weight loss on a high-fat, low-carbohydrate diet. American Journal of Clinical Nutrition, 2010.

Details: 32 obese adults were randomized to a low-carb or a calorie restricted, low-fat diet for 6 weeks.

Weight Loss: The low-carb group lost 6.2 kg (13.7 lbs) while the low-fat group lost 6.0 kg (13.2 lbs). The difference was not statistically significant.

Conclusion: The low-carb group had greater decreases in triglycerides (43.6 mg/dL) than the low-fat group (26.9 mg/dL). Both LDL and HDL decreased in the low-fat group only.

22. Krebs NF, et al. Efficacy and safety of a high protein, low carbohydrate diet for weight loss in severely obese adolescents. Journal of Pediatrics, 2010.

Details: 46 individuals were randomized to a low-carb or a low-fat diet for 36 weeks. Low-fat group was calorie restricted.

Weight Loss: The low-carb group lost more weight and had greater decreases in BMI than the low-fat group.

Krebs, et al. 2010.

Conclusion: The low-carb group had greater reductions in BMI. Various biomarkers improved in both groups, but there was no significant difference between groups.

23. Guldbrand, et al. In type 2 diabetes, randomization to advice to follow a low-carbohydrate diet transiently improves glycaemic control compared with advice to follow a low-fat diet producing a similar weight loss. Diabetologia, 2012.

Details: 61 individuals with type 2 diabetes were randomized to a low-carb or a low-fat diet for 2 years. Both diets were calorie restricted.

Weight Loss: The low-carb group lost 3.1 kg (6.8 lbs), while the low-fat group lost 3.6 kg (7.9 lbs). The difference was not statistically significant.

Conclusion: There was no difference in weight loss or common risk factors between groups. There was significant improvement in glycemic control at 6 months for the low-carb group, but compliance was poor and the effects diminished at 24 months as individuals had increased their carb intake.

Weight Loss

Here is a graph that shows the difference in weight loss between studies. 21 of 23 studies reported weight loss numbers:

Weight Loss on Low-Carb and Low-Fat Diets, Smaller

The majority of studies achieved statistically significant differences in weight loss (always in favor of low-carb). There are several other factors that are worth noting:

  • The low-carb groups often lost 2-3 times as much weight as the low-fat groups. In a few instances there was no significant difference.
  • In most cases, calories were restricted in the low-fat groups, while the low-carb groups could eat as much as they wanted.
  • When both groups restricted calories, the low-carb dieters still lost more weight (7, 13, 19), although it was not always significant (8, 18, 20).
  • There was only one study where the low-fat group lost more weight (23) although the difference was small (0.5 kg – 1.1 lb) and not statistically significant.
  • In several of the studies, weight loss was greatest in the beginning. Then people start regaining the weight over time as they abandon the diet.
  • When the researchers looked at abdominal fat (the unhealthy visceral fat) directly, low-carb diets had a clear advantage (5, 7, 19).

LDL Cholesterol

Despite the concerns expressed by many people, low-carb diets generally do not raise Total and LDL cholesterol levels on average.

Low-fat diets do lower Total and LDL cholesterol, but it is usually only temporary. After 6 to 12 months, the difference is not statistically significant.

There have been some anecdotal reports by doctors who treat patients with low-carb diets, that they can lead to increases in LDL cholesterol and some advanced lipid markers for a small percentage of individuals.

However, none of the studies above noted such adverse effects. The few studies that looked at advanced lipid markers (5, 19) only showed improvements.

HDL Cholesterol

One of the best ways to raise HDL cholesterol levels is to eat more fat. For this reason, it is not surprising to see that low-carb diets (higher in fat) raise HDL significantly more than low-fat diets.

Having higher HDL levels is correlated with improved metabolic health and a lower risk of cardiovascular disease. Having low HDL levels is one of the key symptoms of the metabolic syndrome.

18 of the 23 studies reported changes in HDL cholesterol levels:

HDL Cholesterol on Low-Carb and Low-Fat Diets, Smaller

You can see that low-carb diets generally raise HDL levels, while they don’t change as much on low-fat diets and in some cases go down.


Triglycerides are an important cardiovascular risk factor and another key symptom of the metabolic syndrome.

The best way to reduce triglycerides is to eat less carbohydrates, especially sugar.

19 of 23 studies reported changes in blood triglyceride levels:

Triglycerides on Low-Carb and Low-Fat Diets, Smaller

It is clear that both low-carb and low-fat diets lead to reductions in triglycerides, but the effect is much stronger in the low-carb groups.

Blood Sugar, Insulin Levels and Type II Diabetes

In non-diabetics, blood sugar and insulin levels improved on both low-carb and low-fat diets and the difference between groups was usually small.

3 studies compared low-carb and low-fat diets in Type 2 diabetic patients.

Only one of those studies had good compliance and managed to reduce carbohydrates sufficiently. This lead various improvements and a drastic reduction in HbA1c, a marker for blood sugar levels (15).

In this study, over 90% of the individuals in the low-carb group managed to reduce or eliminate their diabetes medications.

However, the difference was small or nonexistent in the other two studies, because compliance was poor and the individuals ended up eating carbs at about 30% of calories (10, 23).

Blood Pressure

When measured, blood pressure tended to decrease on both low-carb and low-fat diets.

How Many People Made it to The End?

A common problem in weight loss studies is that many people abandon the diet and drop out of the studies before they are completed.

I did an analysis of the percentage of people who made it to the end of the study in each group. 19 of the 23 studies reported this number:

Compliance graph, smaller

The average percentage of people who made it to the end of the studies were:

Average for the low-carb groups: 79,51%
Average for the low-fat groups: 77,72%

Not a major difference, but it seems clear from these studies that low-carb diets are at the very least NOT harder to stick to than other diets.

The reason may be that low-carb diets appear to reduce hunger (9, 11) and participants are allowed to eat until fullness.

This is an important point, because low-fat diets are usually calorie restricted and require people to weigh their food and count calories.

Individuals also lose more weight, faster, on low-carb. This may improve motivation to continue on the diet.

Adverse Effects?

Despite the concerns expressed by many health experts in the past, there were zero reports of serious adverse effects that were attributable to either diet.

Overall, the low-carb diet was well tolerated and had an outstanding safety profile.

It is Time to Retire The Fad

Keep in mind that all of these studies are randomized controlled trials, the gold standard of science. All are published in respected, peer-reviewed medical journals.

These studies are scientific evidence, as good as it gets, that low-carb is much more effective than the low-fat diet that is still being recommended all over the world.

It is time to retire the low-fat fad!


  1. Nice, love the science approach… zero debate needed… low carb all the way!

    • This just helped me make my decision, I am on the right track with a LOW CARB lifestyle. Thanks for all the encouragement backed up by science and real life results. Thanks. :)

  2. Just a quick question, knowing of course that everyone’s body is different and responds differently, what is low carb? Atkins starts you off at around 20 net carbs per day and most other low carb diets don’t really give you an amount of carbs per day, they just tell you what not to eat.

    So in general for most people, what is the range that is considered low carb? Also, it seems as if you recommend more of a paleo diet than low carb necessarily, or are they pretty much the same?

    • Beth,

      In general, I believe low carb is anything lower than or around 100 grams of carbs per day. Atkins induction period (the 20-30g or less of carbs per day) is essentially going to put you in a state of nutritional ketosis – which is fine and dandy, too. I think this is mostly because the SAD (standard American diet) is anywhere from 300-400+ gram of carbs per day (usually much higher).

      Low carb is not necessarily paleo, though they are very similar. Paleo is just eating the way our ancestors ate – anything we could hunt and gather (not replicated in a factory with chemicals). Paleo can still be high carb depending on how many starchy veggies and how many fruits you consume.

      All in all, if you eat REAL food and avoid FOOD-LIKE foods… it’s for the better no matter what!

    • Low-carb basically means “not high-carb”, since the traditional diet includes an excessive amount of them, and the activity level cannot compensate. For the 21st century average person, the healthy amount of carbs required is much lower than what is normally consumed, therefore the name low-carb. An athlete for example, requires a lot of carbs, but probably at the level of what the average person consumes.

      • Just to say that athletes do not need to load on carbs, they would, and some do, much better on a high SAT fat low carb diet as SAT fat provides a long term fuel for the body and carbs do not, as only a very small proportion of carbs goes to glycogen, rendering the rest of the carbs to fat stores and not used properly by body and increasing the amount of insulin in the body too, spiking blood sugar levels.

        We all know how good that is for us. SAT fat is also a food as it is used by the body to make hormones and helps in the cell membrane repair and neurotransmitter repair as our cell membranes are made of fatty acids and our wonderful brain is made entirely of fat too. Fancy that.

        Carbs on the other hand only provide unnecessary energy and that is all. The body has no other requirement of this macronutrient. What are all the government bodies trying to continually tell us, eat lots of carbs. Why, to make money!

        • Mark Johnson says:

          While I agree with a large portion of your statement, I disagree with the why our government tells us to eat carbs. We have 360 million people in America. The only way for a government to provide food for that many people is to to feed them with grains (carbs) that we have plenty of.

          The USDA (Department of Agriculture) has at its core, the interest of the farmers (Agriculture), and have no interest in telling everyone to eat less grain. For the FDA, then comes the money. Fat people mean big business for drug companies, health care, doctors, etc…

          While carbs are not “necessary”, as the body will produce its own carbs via gluconeogenesis (converting protein/fats into carbs), we eat them because they are tasty and provide a high level of satisfaction.

          • Totally agree with you! The food pyramid is a joke. Any article that quotes eating the USDA’s 5-10 servings of processed carbohydrates is ridiculous. Everyone should be doing their own homework on what is healthy. This article is a great example. Thanks!

  3. Stephen Jones says:

    Great article.

    I’ve found that a low carb, low fat and low protein diet is the best. After all, most Americans eat too much protein and the body just breaks it down into sugars, so us diabetics have had to burn off body fat to get our BMI down (way down), and the result is great. Most people who do that, like me, can get off the diabetic oral meds after a year or two.

    • How does that work? Low-carb + low-fat + low-protein… that sound like “just eat less of the same stuff” to me.

    • Thanks for all your work and this great summary Kris!

      Low-fat is indeed the fad. It has been a dismal failure as a mass population experiment, causing more harm than good and needs to go the way of the Dodo.

      Many of us already knew this but the word still needs to get through to a great many more :-)

      Yes Stephen I am also confused (all too easily it seems these days!) :-) These terms usually refer to the percentage of energy (calories) available from each of the three macronutrients — not that we just eat to nourish our bodies with “energy” but anyway…

      In free-living studies the amount of protein tends to stay fairly constant — as you rightly say Stephen, we don’t need a great deal of it on a daily basis (~ 60-80g?). So what tends to change in diet studies are the relative amounts of fat and carbs… as one goes up the other goes down — assuming you want to keep the energy content the same as it was (isocaloric).

      When I describe the way I eat as Low-Carb/High-Fat (LCHF) I see that look on some faces as if they picture me sitting on the couch of an evening, with an huge tub ‘o lard and a big spoon! :-) In fact, given that fat has more than twice the calories per gram of carbs or protein (and assuming my math is correct), a person needing around 2,500 calories per day (not that I count anything these days) could simply substitute 100g less of carbs with 43g of fat and change the profile of their diet from low-fat/high-carb, to low-carb/high-fat. Potentially accomplished with simple changes like eating your chicken with the skin still on, butter (NOT margarine please!) on your vegetables, real full cream in coffee, full fat milk, and yoghourt etc…

      This kind of food is tastier, more satisfying, more nourishing and ultimately more satiating. For me this translates to more available energy and less hunger until it is time for the next meal.

      These terms are relative and as Fred Hahn correctly points out below, with a Low-Fat calorie-restricted diet you may still be eating less carbs than you were before… even if the relative energy from them is the same or higher than it was; because you are eating a smaller amount of everything.

      So the only way to go low + low + low would be to have 33.3% of energy from each. Another way of saying that is to call it high + high + high :-)

      Another confusion I find is the word “diet” — technically, and the way I use it, simply means “what I habitually eat”. I realize that for many it has overtones of a short-term “fix” for “weight*” loss as an example (*really what many hope for its to lose excess fat mass, not the muscle that tends to go along with calorie-restriction). But for me LCHF is now the way I plan to eat for the rest of what I hope to be a longer, healthier and happier life. I foresee no difficulty in my eating this way long-term.

    • Yep, I agree, too much protein does go down the same biochemical pathway as carbs do, but we do need a serving of protein at each meal, along with the high SAT fat for a good balance and the cholesterol in the meat is essential for hormone production, all our hormones.

      No wonder there are so many hormone related disorders as we are so deficient in cholesterol. We have mental health problems (depression, autism, epilepsy, parkinson’s, etc) fertility problems and the need for IVF, and above all heart and stroke problems, and diabetes.

      Cholesterol is the good guy that goes to fight the inflammation and mop up the bad stuff like LDLs. Where does the inflammation come from? Carbs (sugar)!

  4. Etienne Juneau says:


    What an awesome review. I’m sharing on Facebook.

    Have you tried getting this published in a peer-reviewed journal yourself?

    Also, you seem to be spending a lot of time on this site. What’s your motivation? And how can you afford to?



  5. And let’s not forget that ALL of the LF subjects were eating LESS total carbohydrate than before they entered the study. What this means is, what we are seeing is the effects of lowER carb diets in the LF subjects.

  6. What a pity so many of the studies went for such a short period of time (one went for only 30 days, a couple of others for just six weeks). It would surely be beneficial to know the longer term success/failure rates of these studies.

    • A low carb diet can be maintained as long as you like. I lost 18% of my weight in 3 years and am now at a normal BMI. The reason it is so easy is, that you can control hunger. Your body gets used to burning its own fat and you can decrease your meal interval. The body uses fat and you don’t need to snack in between meals, say, 4-6 hours.

      Controlling hunger is the key to successful weight management. What makes LC diet the more important is, that the majority of people are now overweight and in some extent insulin resistant. This has been ignored in diet recommendations. They are planned for the minority, normal weight people.

  7. Hi

    Nice review but I have to say that almost all of the studies you just reviewed were conducted with either diabetic, overweight subjects or those who had elevated risk factors for CVD. Correct me if I’m wrong here.

    Thus, I would like to hear about studies using normal, active people. How does low carb work for them?

    For example, if an active woman is eating between 2000 and 2500 kcal/d and training (eg running) an hour or two a day, then what happens if she restricts her carb intake well below the amount she’s previously eaten (from somewhere between 200 and 300g to below 100g)? Does her hormonal system protest and does this change in diet distract her metabolism by turning the body into a starvation mode where all the food she eats is turned into fat because the body’s trying to “survive”…?

    Just something to think about, as obese and normal weight individuals are completely different and what works for one does not necessarily work for the other..


    • Hello Ida.

      You’re absolutely right. The studies are done on people with overweight/obesity, type II diabetes and metabolic syndrome. There are also a few other health problems that respond well to a low-carb diet, but these are the most common ones.

      I don’t necessarily recommend a low-carb diet for people who are metabolically healthy and physically active. Athletes, runners, bodybuilders, etc. need more carbs to function optimally.

      A low-carb diet probably won’t put these individuals into starvation mode or anything like that, but it could definitely decrease physical performance.

      There are some athletes though, especially endurance, that function well on a strict ketogenic diet, but it’s not something I recommend for healthy people as it is unnecessary.

    • The body goes into a ketogenic state, like a starvation state, however that is how our ancestors ate, up until the 19th century and our bodies have not changed. Having more fat provides the long term fuel needed for a long run. Carbs only make one more hungry as the hormones that say you are full do not recognize carbs as a fuel.

      And only a very small amount of carbs is actually stored in the liver as glycogen anyway. The rest just goes to fat stores. Where as fat is processed differently and the triglycerides can be utilized to fuel readily. The science (proof) is all there, all we need to do is check it out for ourselves.

  8. Very interesting that the one study which included the Mediterranean diet performed equally well to low carb.

    I have tried both and whilst I had excellent weight control on low carb, once I reintroduced rice I felt much better. I still do not eat wheat at all, but I sometimes eat potatoes, beans, lentils and more often, rice. I also allow myself milk now in moderation. I am at my ideal weight and my variation (no bread) of the Mediterranean diet works fine to keep the pounds off.

    Note, I have never been obese. My goal was always a six-pack :) I am 45 years old.

  9. It’s interesting that in many of these studies optimum weight loss stands at around the 5-6 months mark, with increase occurring after that point. I wonder why this is. Could it be that most people get bored with a diet after about half a year, or is there something metabolic going on?

    • Yes, unfortunately this is common in most free-living weight loss studies. People give up on the diet and start eating the same old stuff again.

      But those that stick to it will see lasting, long-term results.

      • Mike Donelly says:

        You never know how much people in these studies cheated.

        Perhaps the best study would be carried out in a prison where they can really control what people eat :)

        • Well there was a study conducted at a Vermont prison in the 1960′s as discussed here…

          Junkfood Science – The first Law of Thermodynamics in real life

          But in that case a Dr Sims was trying to see how obesity would affect well-motivated, volunteer inmates (offered early parole). They were consciously overfed but failed to gain the levels of weight as CICO would have predicted.

          I can’t say as I am a fan of rigidly controlled “diets” such as in a metabolic ward — sure they control as many variables as possible but they also take away the huge element of “real world” and what is sustainable, over the long-term, in real life. No doubt I would eat differently if I had a trained chef preparing and serving all my meals for me!

          • Mike Donelly says:

            Yes I quite agree, but at least the scientists would be able to control out the variable of choice for which there is too much latitude when people are out of sight.

            There is no way to conduct a 1 year study and control exactly what people eat in a domestic setting.

  10. @Mike Donelly

    Strictly scientifically speaking, you’re right. But! One way to make sure that most people preferentially choose food that is bad for them (carbage) is to make sure their income is low. Proper food sadly is not the cheapest choice out there. That is the status quo, so we’re all part of a junk-food study. And we know what the results are…

    • Hi Robert. I think it is more education than income in as much as freshly prepared food can be just as cheap, if not cheaper than junk. A diet rich in vegetables with carefully prepared cheaper cuts of meat can be very reasonable. And there are plenty of good recipes out there.

  11. Mike Donelly says:

    Another thought struck me as I was driving home this evening. In many of the studies above there was weight loss for the first 6 months and after that it tailed off. For studies that continued longer there was sometimes a mild subsequent gain in months 7-12, both for low carb and low fat diets.

    Given that these people were unlikely to have reached a normal BMI as the overall weight loss was modest, could it be that the body takes about 6 months to accustom itself to burning fat for energy? Inuits (who traditionally followed a high fat low carb diet) had abnormally large livers. Could it be that the liver is enlarging during the first 6 months of low carb dieting? My hypothesis: Once the body gets used to burning fat more efficiently, weight loss tails off.

  12. Thank you – this was useful. I wonder, what about combining low carb and low(er) fat diets, e.g. favoring good sources of Omega 3s fish/nuts/chicken for protein sources over say bacon or hot dogs. I wonder if during a ketogenic diet you could get extra benefits from having the “right” fats in your diet? Also, I would say that the Mediterranean diet in the Shai study – seemed to have good maintenance, no?

    • There are some versions of low-carb/keto that emphasize unsaturated fats. These are also very healthy, although no study I know of has compared it to a standard low-carb/keto diet with animal fats.

      Yes, the Mediterranean diet did pretty well in that study. A little bit less weight loss in the beginning, but they managed to maintain the weight they lost pretty well.

  13. Thanks Kris – I really like how un-dogmatic your site is. That you recognize that what works for one – might not work for another. That we should use both population evidence… and personal evidence.

  14. Other than being selected from a relatively recent time period, were these studies randomly selected from a larger number of similar studies in the same time period without confirmation bias? Similarly, did any of these studies follow their participants following the original studies?

    • I included all the RCTs that were clearly comparing low-carb and low-fat diets. I’m sure there are some more that could be found by digging deeper into the literature.

      Not aware if any of these studies had longer follow-up.

  15. Garth davis says:

    As the A to Z study points out, the effect fades long term. More importantly, the low fat groups were never on a low fat diet. A low fat diet should at least be below 20% fat and if you really want to reverse heart disease then it should be 10%. These studies vary between 30 and 38%!!

    That is not low fat! So these studies show a low carb diet vs a standard junk food diet. Initial weight loss has been shown to be partly water related as you eliminate glycogen. Furthermore, recent low carb studies show increased c reactive protein, increased urinary cortisol, and increased acidosis.

    • Weight loss effects fade in the long term, that is a problem with all weight loss studies because people eventually give up on the diet.

      What these studies pretty clearly show is that telling people to eat “meat, fish, eggs, vegetables, nuts, seeds, fats, high fat dairy and some fruits” is better than telling them to eat “lean meat, fish, little eggs, lots of whole grains, fruits, vegetables and low-fat dairy products and choose vegetable oil.”

      I’d like to see these studies where low-carb increases CRP, cortisol and causes acidosis…

      Btw, there is literally NO evidence that a 10% fat diet will reverse heart disease. If you look at the A to Z study (12), that’s exactly the diet they were trying (which is almost impossible, apparently) to follow and they did terribly.

  16. Garth davis says:

    Sorry but this is my career and you are very far off. Both Esselstyn and Ornish demonstrated that you can reverse heart disease on a 10% fat diet. I visited them and actually saw the angiograms.

    There is literally hundreds of articles on metabolic acidosis and hyper cortisol from meat diets. http://jama.jamanetwork.com/Mobile/article.aspx?articleid=1199154

    I treat thousands of patients for obesity. All of them have done paleo, Atkins etc. they respond extremely well to a plant based diet. They just need to be taught how.

    The Adventist health studies and Epic PANACEa studies have shown that vegetarians weigh less than meat eaters on average.

    • Do you even know what you are linking to? The study you linked to actually shows that low-carb diets boost metabolism compared to low-fat/low-GI diets during weight maintenance. Plus you can’t just look at ONE study to make a conclusion, there are 23 studies linked to within this very article and most of them show great health benefits and significant weight loss for low-carb.

      There is no evidence that a 10% fat diet can reverse heart disease! Please show me a study where diet is isolated as the sole variable. Ornish also used exercise, meditation, smoking cessation, etc. There are so many big confounders that NOTHING can be concluded about diet from his trial. Saying that a 10% fat diet can reverse heart disease is pure speculation and I personally do not buy it. Anecdote is NOT scientific evidence.

      When Ornish’s diet was compared against Atkins in a randomized controlled trial (the only difference between groups being the diet), Atkins did the best.

      See #12: http://jama.jamanetwork.com/article.aspx?articleid=205916

      I am well aware that vegetarians weigh less on average than meat eaters. That’s because they’re also more health conscious and more likely to exercise. Correlation does not equal causation. If you were to measure health conscious meat eaters against health conscious vegetarians, the difference would likely be smaller or nonexistent.

      Vegetarians also tend to have less muscle mass, which is a pretty significant contributor to body weight. Maybe that alone explains their lower weight.

    • Jacob Lynn says:

      @ Garth,

      First, Ornish’s approach relies on lifestyle modification, which Kris correctly points out cannot be taken as an independent variable; in the end this vitiates your ability to claim that a vegetarian diet is solely responsible for the angiographic evidence you claim to have seen.

      Second, a Pubmed search ‘Low carbohydrate diet and CRP’ reveals clear results: lower carbohydrate intake reduced not only CRP, but also vascular and intracellular adhesion molecules and inflammatory cytokines; which contradicts your claims otherwise.

      Third, the favorable changes in the lipid panel observed on a low carbohydrate diet cannot be easily discounted. On the low carb diet triglycerides plummet, which in turn lowers VLDLs and prevents their turnover to intermediate density lipoproteins (ILD) and the resulting transformation of ILDs into small, dense LDL particles with apolipoprotein B expression. The increase in LDL particle size and the decrease in LDL particle number seen on low carbohydrate diets outstrips anything full carbohydrate, low-fat diets can achieve.

      Fourth, this is also how I make a living, but I deal with things after the fact. What I struggle with the most in counseling patients is the absurdities of thought which permeate medical recommendations. My goal is to present dietary recommendations that are physiologically accurate, that is, which diet correlates best with optimal human health. Thankfully, the wellsprings of current medical recommendations are drying up quickly.

      @ Kris
      I assume, if incorrectly I apologize, that you are employed in the fitness industry. To you I say that I recommend low carbohydrate diets to currently healthy people for the same reason you recommend exercise to them. Exercise not only controls weight and improves strength and conditioning, but also improves cholesterol metabolism and energy utilization, promotes proper endothelial function, and delays the onset of chronic illnesses.

      Diet does the same, and as I stated in my response to Garth, but more so to you, I recommend the low carbohydrate diet as that which correlates best with optimal health and longevity. My reason for this is because diet is even more an ingrained process than exercise, and persists long after a person loses interest in exercise or the ability to do it regularly. As the old aphorism goes: An ounce of prevention is better than a pound of Statins—or something like that.

      • Elle London says:

        I read that too and got depressed having around 10 stone (140 lbs) to lose. I wonder though if the weight loss tails off, but the fat loss continues. I wonder if their measurements got less from months 7 to 12. After all, to some extent weight is just a number, although my knees know differently.

        I am still depressed though to think of being healthy blood test wise yet still having stones to lose despite eating low carb high fat for the rest of my life. I need to lose weight to stop my knees and back hurting. I don’t mind most of the time not eating crap, but would like to see some results.

  17. Came across this article after another one that believes the opposite.


    Makes things confusing…

    However, I couldn’t get hold of articles the author cites without paying.

  18. I’ve been trying to understand re-esterification as I have recently learned that prior pre-eclampsia carries with it a lifetime increased risk of CVD.

    The suspected link is endothelial dysfunction, so I’m wondering if during rapid weight loss there could be a temporary increase in unfavorable CVD disease markers. That was my hypothesis as to why the “good fats” were especially important during this phase.

    Preeclampsia also correlates w/ later kidney disease, so I’m mildly concerned that I have a low level of protein in urine while in ketosis and caloric deficit. I’ll probably seek a second medical opinion if it persists but as the pre-eclampsia connection is not yet widely appreciated in lay population, I thought I’d remind people of this issue.

  19. Did any study say who lost more body fat? Why are these studies not distinguishing between fat and muscle. If people are losing muscle then they are not doing their body as much good as they think.

  20. Karl Wheatley says:

    Despite the title of your blog post, of the 19 articles I could access, NONE of the studies you reviewed here really studied truly low-fat diets.

    Thus, you can’t claim anything based on this review about the effects of low-fat vs. low-carb.

    I was able to access 19 of the 23 studies, and none of them are low-fat diets of the sort advocated by Ornish, Esselstyn, or McDougall. Thus, the lit review really compares medium fat to high fat diets.

    Most of the interventions were 30% calories from fat in the “low-fat” group–meaning that they were triple the fat advocated by Esselstyn, and quadruple the level of fat recommended by McDougall. The USDA food pyramid was ~30% of calories from fat, but the recommendation was only that high because of the influence of the food industry. Without food industry influence, the USDA guidelines would be well below 30% calories from fat, and no one would be claiming 30% is “low- fat.”

    A few of the studies were 25% calories from fat, but only one was under 20% calories from fat, and significantly, in that study (18% calories from fat), the “low-fat” group did quite well. Imagine if any of these studies compared 10% calories from fat to high fat diets!

    The low carb dieters slightly outperformed the medium fat dieters (falsely labeled “low-fat”) in these studies, but we know from other studies that truly low-fat diets substantially outperform these medium fat diets (AHA, NCEP, food pyramid).

    In short, if people want to follow the recommendations of Ornish or Esselstyn or McDougall, none of these studies provide any relevant evidence to the contrary.

    • Karl, this article is about studies that compare a low-carb diet to the typical USDA low-fat diet, which is what most people assume when one uses the words “low fat diet.”

      You are right that it is not about comparing low-carb with the very low-fat diet advocated by the vegan docs. However, #12 (Gardner, et al.) compared Atkins vs Ornish. The people had a really tough time sticking to the Ornish diet and did badly, while the Atkins group did the best out of all 4 diets. More about this study here: http://authoritynutrition.com/low-carb-vs-vegan-vegetarian/

      The ONLY study that at least tried to compare low-carb with a very low-fat vegan/vegetarian diet showed clearly that the low-carb diet did much better.

    • Karl, your complaint is a common one. I could complain they didn’t actually test low-carb, since the results don’t reflect what the best can do. However, this suggests there’s a difference in how difficult it is to do low-fat vs low-carb. Maybe low-carb is easier. But then maybe it’s easier because it’s more effective. But then again, maybe it’s more effective because it’s easier.

      We can’t distinguish at this point. Anyway, you gotta wonder why we’d try something that’s more difficult, when we can do something much easier with good results. But here again, that complaint is addressed easily, as Chris Gardner explains that every single subject got their own copy of the diet book, and they all read it completely with the help of a competent teacher (I say teacher, but it’s just some guy/girl with adequate training for this purpose).

      Anyway, the point is it’s highly unlikely that any subject didn’t understand the diet, thus that they didn’t – or at least try to – follow the instructions as written. Maybe it’s the diet books themselves, they’re just too poorly written. Who knows.

      Your complaint also assumes that if they’d done Ornish properly, then ALL subjects would have done better (not just the best adherent of the group). Well, we could assume the same for the other 3 diets in the A-TO-Z study for example.

      The correct logic is as follows: Since as a group, Atkins did best, then it follows that the best of the Atkins group must have done better than the best of the other 3 groups. In a lecture, Chris cites the example of one woman who lost 50lbs on Ornish. Well, he could have cited a better example in the Atkins group too, since that group as a whole did better than Ornish. Note that Chris is a vegetarian, and his study showed him that his personal diet ain’t the best for the rest of the world.

  21. Robin Westbrook says:

    I am really disturbed by this entire discussion as it is all about normal, healthy people. I am a Type II Diabetic (controlled) who just had my gall bladder removed due to ACUTE pancreatitis. I NEED to have an eating plan that is both low-fat and low in simple carbs. I should have foods with 2 grams of fat or less and am allowed only 30 carbs per meal.

    This is disappointing because I am given orders by the doctors but no information, then what information I am able to find comes in the form of an argument over carbs vs fats. Can someone direct me to a site where I might find some accurate information that fits?

    • Stephanie Ann Serpas says:

      Hi Robin,
      You may visit http://www.eatright.org, all information is evidenced based and written by registered dietitians, the TRUE nutrition experts. You may also visit http://www.diabetes.org for more information as well.

      Also, visit http://www.dietitian.org to search for an RD and get help for your individual dietary needs.

      Hope this helps,
      Dietetic Intern 2013-2014

    • I am in the same boat as you. My husband is type II diabetic and developed severe pancreatitis in 2010 due to high triglycerides. The dietitians told us to follow that same diet as you. It has been very difficult and stressful trying to plan these meals.

      I’ve been looking for different alternatives and am too very confused by all the conflicts. I like the ideas here for the LCHF, but I am scared to try it on him without being able to monitor his triglyceride levels frequently to be sure he’s ok.

      I’ve been doing it myself and feel better, fuller, and healthier and have lost weight, but I’m not diabetic.

    • Elle London says:

      You might find help at Dietdoctor.com. Check out Andreas Eenfeldt. If diabetes is the main concern, then cutting out starchy carbs, fruit and all sugar is the first step. Eat like they used to post WWII. Low fat does nobody any good, apart from the low fat food manufacturers. Follow the money.

  22. The problem with these studies is that some of them state “low fat diet” as being 20-30% or even more calories from fat. HOW IN THE WORLD IS THIS LOW FAT? Second problem is that these are all based on short term weight loss and results (not blaming the studies, it’s obviously easier to do a study based on short term results, but just pointing this out).

    We need to look at LONG term results based on a real low fat diet (10% or less). People following the 80/10/10 diet (80% of calories from carbs – mostly fruit, 10% from fat, 10% from protein) are seeing tremendous results. LONG term. Lean as hell, and eating as many calories per day (2500/day minimum for women!).

    Not to mention that Asian cultures have been eating the majority of their calories from CARBS for thousands of years and never have seen diabetes, heart disease, obesity, until the Western diet was introduced.

    Either way, whether it’s low carb or low fat, at least these diets are better than the standard american diet. Or so we can hope.

    • The studies are comparing against the typical USDA low-fat diet, which IS a low-fat diet (just not ultra low-fat).

      Study #12 (Gardner, et al.) compared Atkins vs Ornish (80-10-10). The Ornish group had trouble sticking to the diet and didn’t do well. Atkins had a very clear advantage in that study.

  23. Have you come across any studies that looked at incidence of cardiovascular events between LC and LF diets? So far all these studies are looking at the risk factors for these events but not the events themselves.

  24. Leigh MacKay says:

    Two heart attacks and an Aortic Bifemoral Bypass within the past 12 years and I’m wondering what to do about my diet. Cholesterol is the issue.

    If you saw me working out in the gym, you’d have no idea I’m suffering with elevated cholesterol levels. I look years younger than my real age. But I’m struggling with finding a diet that will benefit my cardio vascular system.

    I’m a little obsessive so when I go on a diet plan, I’m totally there. First we went on the Rosedale diet – limited grains but fat is okay. I lost weight for sure but had some side issues – pH was off the hook acidic, something was aggravating my GI, and something was triggering what I call a tingle in my left side.

    Then we shifted to Esselstyn – zero oils, no eggs, no dairy, vegan. This diet is challenging. I’ve not lost any weight and am quickly growing tired of eating salad.

    Somewhere in the middle we will find the truth?

  25. I agree that low carb is much healthier than low fat, but I don’t think the actual weight loss can be significant on the standards of these studies.

    You have to take into account that high carbs means higher water retention. When I went on a keto diet I dropped 10lbs in a week, which was almost all water weight, and this has remained off.

    • Yes but as you can clearly see from the graphs, people continue to lose more after the first week.

      Low-carb does cause a lot of water loss in the beginning, at least for some people, but I can’t possibly see how it’s a bad thing to get rid of 5-10 pounds of water that your body doesn’t need.

  26. The adventists are a very good population to see the effects of a vegan diet in comparison to a non-vegan diet as the people tend to have a very comparable lifestyle, but differs in their dietary habits. So most of the confounders are not present here (such that you claim that vegans tend to be more health-conscious).

    Vegan adventists always do better.

    Less CHD, less diabetes, less obesity, less high BP, etc etc.

    In regards to the studies presented here, here are most of the problem with them and why they don’t tell us much.

    1) They usually are not calorie-matched. We know that LC usually bring more spontaneous calorie restriction.
    2) They are not low-fat.
    3) They are not high in fiber, which means that the participant clearly were not eating plant-based whole food. I average 60g of fibers a day. Most participants barely get 15g of fibers in most of these studies.

    Basically, they are comparing a crappy diet against a LC diet. No wonder the results are what they are.

    You claim to be evidence-based. Why don’t you put all of this into the proper context, considering all level of evidences? RCTs can tell us just so much about nutrition. Prospective cohort studies are the gold-standard in this field, as nutrition related effects takes decade to manifest.

    First, there is no long-lived population that did well on a LC diet. The eskimos are the closest to it and they were one of the most diseased population to have been studied.

    Pre-WW chinese have been extensively studied. They were eating a low-fat, low-meat, low-salt diet, and CHD and cancer rate was extremely low.

    Most long-lived population, such as the Okinawans and the people from the blue zone, eat a plant-based, low-meat diet.

    It was noted from many authors long ago, as far back as early 1900′ that high-fat, high protein animal diet were disease inducing.

    This post should in no way be used for someone to decide to go low-carb. There are plenty other lines of evidences to consider, and anyone looking at that objectively will come to the conclusion that low-carb is not supported by the whole body of evidence. Plant-based nutrition, low-fat, high-fiber, is.

    • Any diet that cuts processed foods will be healthy, including plant-based diets based on whole foods. But the health benefits have nothing to do with avoiding unprocessed animal foods.

    • @Frank, if we look at reversing the trends of obesity in 1st world countries, which is what obesity is… a 1st world disease, the RCT’s are valid. To your points:

      1. A LCHF diet has no calorie restriction, and no calorie counting.

      2. Why do you need “High Fiber”, I for one, and many others eat a smidgen of vegetables, have done for years, and have perfect blood work. Am I some sort of strange metabolic freak, no… high fiber, as with low fat, is overrated. Without seeking out extra fiber, or high fiber foods, you get plenty with a normal serving of vegetables, and the piece of fruit here and there.

      3. Yes, agreed. Nutrition related effects take decades to appear. A low fat diet since 1985 has resulted in millions of obese people worldwide.

      4. As far back as 1917, the Diabetic Cookbook had “Foods Strictly Forbidden” sugar, starches, breads… nothing has changed.

      5. As for a long-lived population on low-carb. I would say that prior to the mid 1980s, every 1st world country was on a balanced diet, higher in fats and proteins, and lower in carbs. The problem is that people have abused carbohydrates, and now need intervention. They need to radically reverse the effects, and eating a “balanced” diet will simply keep them where they are.

      You cannot take a small subset of the global population such as the small rock Okinawa, and apply that to the 1st world population.

  27. Kris, love the article. I think it is important for people to understand that a low carb diet should be Low Carb and High Fat (LCHF), and not Low Carb with High Protein. The difference is that protein is converted to carbs ~58%, and an excess amount of protein will offset the benefits of a low carb diet.

    I did read a post by Leigh Mackey on wondering whether it will help with Type II. There is no question that it will. Leigh, look at DietDoctor.com, he is a Swedish Dr. and has a video of a presentation he gave at a conference in LA in 2011. Type II Diabetes is a modern disease created by our abuse of carbs, and there is no correlation between a high fat diet and heart disease, in fact… it is the opposite.

  28. Mel Conway says:

    Thank you for this review – it’s helpful to have all this information together. It must be noted however that these studies focused on weight loss among overweight people rather than a ‘healthy diet’. The comments about weight loss tailing off after 6 months has also been noted by a Swedish Expert committee’s evidence based review of obesity management, and related to difficulties in maintaining any extreme diet in the long term.

    However, I was particularly struck by study 16 where the Mediterranean diet appears to achieve good long term weight loss results (as good as low carb), and without the 6 month dip. The Mediterranean diet is recognised as the most heart healthy, has good evidence of increased longevity, and is not faddy.

    Although high in fats, the type of fat is important, coming from olive oil, nuts, fish, etc (mono-unsaturated). So rather than adopting high fat diets indiscriminately, should we not conclude that a healthy diet will give both long term weight control, and improved life expectancy, but also be sustainable?

    • “…that a healthy diet will give both long term weight control, and improve life expectancy…”

      That statement is useless!

      A healthy diet BY DEFINITION does all of that. Yet what is a healthy diet?

      And you don’t define a diet as healthy in the first step and then claim it should work its magic.

      You look at the data first and then come to a hopefully sensible conclusion as to what works for the majority of people.

      If the data says that low-carb high-fat works best, then that makes it a healthy diet.

      Until LCHF is universally accepted and has become part of common knowledge again, it makes more sense to call it low-carb high-fat (or Banting) and not just a “healthy diet”. People will interpret whatever they want when they hear “healthy diet”.

    • @Mel

      When you look at the current recommended diet of low fat, it just doesn’t hold up to scrutiny, as it simply increases the body’s ability to store fat through the over abundance of carbs.

      My theory on the diet plans and why they tend to level off, if not tick upwards, has to do with insulin spikes. Initial low carb dieters see fast drops in weight, in large part due to water loss as carbs are shed for energy, however, with very little carbs incoming, the body slows down the rate of burn due to famine like conditions, and until the insulin spikes resume, the rate of burn will remain low. If this continues for an extended period of time, more and more protein is converted in the liver into carbohydrates, and if you are insulin sensitive, and prone to fat storage, more fat will now be stored, even though you are still keeping carbs low. The best way I’ve seen to offset this is through carb cycling, which is a high insulin spike due to incoming carbs on one, or two nights per week.

      Also, a diet that works for someone at “normal” weight, will not work for someone who is obese, as they have lost the ability to process sugars the way normal people do, and need a more intensive approach… i.e., Low Carb High Fat.

    • Thompsonpat says:

      Mel – moderate approaches never sell newspapers. :)

      I also wonder if there are certain time periods where we are extra sensitive to the kind of fat in our diet. Anecdotally, only just my experience – I have lost about 30lbs and I tend toward low carb – moderate fat of mediterranean type. Fish/olive oil/some hard cheese/the occasional dollop of whole fat yoghurt.

      But I still have some troubles with inflammation and perimenopause. An acupuncturist / chinese medicine person told me to try adding beef bone broth to my diet and this seems to have helped. I have fewer hot flashes (even less than just from losing weight alone) and some of the other symptoms also seem better.

      Again no RCT – but a little of both (mediterranean and BEEF knuckle soup) seems to work for me. But I have found if I stray or add too many carbs -I don’t feel well and the inflammation returns. Will do blood work again in a month and see what if any progress. Historically I had low cholesterol but not as much HDL as conventional wisdom suggests I should have.

  29. Alex Sapounakis says:

    And the winner is … the Mediterranean Diet due to excellent results, proven to work for many generations, and longevity of life. Anyone wonder why? It’s the religion which forbids red blood meat for over 180 days a year, as well as other changes in diet during the course of the year. Of course during the last couple of decades more and more McDonalds, Burger King have sprouted and Coke and it’s really SAD (Standard Am. Diet) how people even there are getting fatter slowly.

    Want to know more about the healthiest diet in the world which leaves you satisfied but at the same time gives you an appreciation for food? Look up what and when the Orthodox religion allows and NEVER buy anything that comes out of some stinking box.

    Good luck to all and thanks for an excellent evaluation Kris . You can never satisfy everyone and there will always be somebody that wants to prove someone wrong, but after doing sufficient research myself I agree with your findings and one should be able to ‘tailor’ what diet to start/finish or use for maintenance. Myself, I’m doing the Low Carb High Fat for 20 lbs, but switching over to the Med Diet afterwards so I can enjoy everything, but in moderation.

    • Alex, congratulations on sticking with the LCHF diet. While the Mediterranean Diet is good, it unfortunately is not for everyone. Not because people wouldn’t benefit from it, because for some people it is far outside of their cultural food norms.

      What is important is that people look at what the principles are of the Med Diet and try to apply those to their daily diet. As for the Standard American Diet (SAD), there is none. There are far too many cultures in America for any single diet to the norm. I would call it the Standard Marketing Diet, as people gravitate to over-hyped TV and Supermarket advertising.

  30. Hi Mark.

    Not sure my comments will make it through.

    Truthfully, I don’t even know why I’m wasting my time debating this as my mind is pretty set in regards to the scientific consensus and LCarbers are also pretty set in their mind so it’s kind of a waste of time.

    1. A whole food, plant based diet either, as energy density for animal product is much higher so you can eat much more food on a whole food plant based diet. I had to eat 5 medium-big sized sweet potato for my dinner yesterday to barely get 800 calories.

    2. Fiber is a good marker of food quality. Someone who does not get much fiber does not consume much whole plant based food.

    3. You are confused. People never did the low-fat diet as promoted. People have been junking on refined carbs and meat for the past years and over-eating pretty much of everything.

    4. Yes, who ever said diabetic should be eating sugar and refined grains?

    5. Again, whole food carbs are not a problem and never have been.

    I believe that long-lived populations are part of the evidence to be considered when making nutrition recommendations.


    • @Frank,

      1. Who counts calories?… a Low Carb, High Fat diet is not calorie counting based.

      2. Why do I need to eat a lot of plant based foods… not to say I don’t eat a decent amount, but I and other “Low Carbers” prefer a more meat and two veg kind of dinner… with a healthy amount of fat in the process.

      3. Completely agree… the creation of High-Fructose Corn Syrup (HFCS) has artificially introduced excessive amounts of carbs that were just not present in the past, so it’s not like we were eating lower amounts of carbs as part of a plan, they just were not available. As a loose example, a movie soda was 8-12oz…. now you need a catheter for the almost 1/2 gallon you get.

      4. The USDA says so. Look at the Food Pyramid. The foundation of which is grains. Carbohydrates break down into glucose, either slowly as in whole grains, are fast as in simple sugar, the net result is excessive amounts of glucose, which the body is quite happy to store as fat for us to use later.

      5. While I agree whole food carbs should not be a problem, they are, as we have artificially changed our food sources to include fake “sugar”.

      6. Agree… Jamaicans typically have a very high life expectancy, very little beef… high amounts of fish, chicken, rice and vegetables. This is now changing thanks to the introduction and Americanization of the world’s food.

      One thing to consider and remember. When someone is obese, they have changed the way their body works with incoming energy, and have lost the ability to manage it the way “normal” people can. For these people, it is critical to not raise insulin levels, allowing the body to work with the energy reserves (fat) that it has.

      Lastly…. a lot of this calorie restriction dieting is crazy, as it only makes people “Skinny Fat”.

  31. Hi Mark.

    Last time :)

    1. I’m not sure where this point is going actually lol. Carbs have a mean 4 calories per gram whereas fats have a mean of 9. That’s a pretty big disadvantage right there for a high-fat diet to overcome. You can eat a lot more food on a high-carb diet than on a high-fat diet for the same # of calories. Also, a lot of people count calories. It is still the best way to influence body composition and ANY diet should be well-planned. I know how much calories I get from each meal as, as I said, it’s easy to not eat enough on a plant-based diet as you need to eat a lot of food to get your daily kcal recquirement.

    2. Well because you have to get energy from somewhere. You choose to get it from animal fat an protein. I believe that the current evidence show that this is most likely harmful. So I choose to get my energy from plant food instead. Also, do you ignore all the trials showing positive impact of fruits consumptions on many aspect of health (cognitive function, cancer prevention, etc etc)? Plant for the win seriously.

    3. Yes, but I hope you can make the difference between a soda and a fruit. And between white bread and quinoa.

    4. Yes, foundation is WHOLE grains. Look this up, there is a negative association for whole grains with type II diabetes. They were right to say so. Health agencies never said anyone should eat more sugar and refined carbs.

    Whole Grain, Bran, and Germ Intake and Risk of Type 2 Diabetes: A Prospective Cohort Study and Systematic Review


    Look at this study too while you are here and think about it for a moment.

    Consumption of red meat and whole-grain bread in relation to biomarkers of obesity, inflammation, glucose metabolism and oxidative stress.


    5. How are whole carbs food more sugary now than they were? How is oatmeal richer in sugar now? How is brown rice more sugary? Sorry that does not make sens. I’m not sure you have a good grasp what whole-grains are.

    6. China used to have a very low-prevalence of obesity and CHD. They were eating a traditional high-carb, plant based diet, low in animal product. Immigrant chinese that have adopted the north american lifestyle or wealthier chinese that have started eating lots of meat and refined products have been started to get obese and develop CHD. Clearly the problem is not whole food carbs. Is it the refined carbs? yes. Is it the meat? Most likely as when you look at the whole body of scientific evidences, there are many reason to believe meat is diseases inducing. All the lines of evidences are converging in the same way. Don’t miss the forest for a tree.

    Metabolically broken? You know, I have a ms degree in nutrition I work with obese clients in an obesity clinic. Making people lose weight and regain their health is my job. I used to be pro-paleo, pro SFAs and pro meat a few years ago but I changed my mind based on a better understanding of the science. Now I put mostly all of my client on a flexitarian diet, ie, whole plant based food with a little meat here and there (3-4 times a week). I have a lot of morbid obese clients that also suffer from type 2 diabetes. The better the adherence to my plan, the better the results. I’ve yet to see someone who cannot lose weight when he follows my recommendation. I had a 300 pounds, 5’5 women steadily losing weight in the past months (she’s down 80 pounds now) while highly increasing her complex carbs. She eats mostly only fruits, vegetables, beans and whole grains now.

    I don’t think complex carbs is a problem even for very obese individual. Animal fats and fats in general, on the other hand…. but I won’t get there (but you can read up on it!).


    Thanks for the discussion Mark!

    • Frank, your last link refers to a mouse study. A priori, we can’t directly transfer those to humans. We have to do a human experiment to draw definitive conclusions. But since we’re on the subject of mice, here’s a mouse study that looks at the effect of new hepatic fat on various substrates homeostasis:

      “‘New’ hepatic fat activates PPARalpha to maintain glucose, lipid, and cholesterol homeostasis.”


      Like I said, we can’t directly transfer the results of a mouse study to humans, we have to do human experiments. I mean, we’re not trying to figure out what to feed our pet mice, right? Nevertheless, we can devise a hypothesis, which we can then test on humans. So, the hypothesis here is that eating more fat will maintain substrates homeostasis, i.e. blood glucose, lipid, cholesterol will return to normal.

      Do we have human experiments like that? Yes, that list of 23 experiments has a component of “eating more fat” in the form of low-carb, since low-carb is inherently higher fat. Incidentally, a common mistake of new low-carbers is to continue to eat low-fat at first, and suffer the typical symptoms: Lethargy and mind fog mostly. But once they add more fat, those symptoms subside.

      And as we can see in the A-TO-Z study for example, those substrates (BG, lipid, chol.) do return to normal, better than the other 3 diets tested, which confirms the hypothesis generated by that mouse study I linked to above.

      I understand that you believe observational data like the Okinawa population should be considered when devising recommendations. But experiment trumps observation, and above we have a clear example of that principle.

      As a side note, you make it sound like you’re frustrated with the discussion, you can’t convince us. With respect, I suggest you select data of a higher quality than what you already provided. Personally, I dismiss observational data outright, and only consider experimental data to draw my own conclusions.

  32. Lots of great data and comments… Thanks!

    When folks that normally eat fructose stop eating fructose, fat decreases, especially peritoneal fat and triglycerides. Avoiding all carbohydrates is one way to do it but is unnecessary, expensive and hard on the planet.

    • As I understand it, it is not possible to eat no carbohydrate if you are including leafy veg and salads in your diet, as you allegedly should. What we are avoiding is the starchy carbs and sugar I think.

      • Elle,

        When on a low carb plan, you must consider sugars in vegetables such as carrots. One way to think of this is to avoid veggies that grow underground, as they typically contain the most sugar. The goal on a low carb plan is not to avoid all carbs, but to keep carbs very low, and in return… you can eat a lot more good fat and protein, as a low carb diet is not a low calorie diet.

  33. Julie Balulie says:

    All I know is I have finally managed to lose tummy fat and have energy by cutting out milk, grains (kind of Paleo) and beans/legumes.

    I used to follow Fuhrman, all veggie plant diet with eggs but ended up in the hospital with anemia so severe I required infusion of iron. A bit of meat, lots of fish, no grains or grasses, heaps of greens and low sugar fruits, eggs and I feel great.

    Is that low carb? Oh, arthritis gone and cholesterol down for the first time in five years it’s been creeping up on the normal low fat.

    • Julie,

      What you have is a low-carb diet, and you’ve seen the benefits first-hand. The “normal” low fat diet has resulted in an ever increasing world-wide obesity. Elle’s comments about sugar in veggies is correct.

      Veggies underground will typically have more sugar than above ground veggies. The only thing I would add is more good fat. Coconut oil, olive oil and avocados. As you’re anemic, look to eat more beef/liver.

  34. I did low carbing for a long time, I lifted weights 5-6 times per week. I started to experiment with low carb back in 1998 and have lost a lot of weight but the issue here is that the muscles are lost too without glycogen.

    We are all different, some get used to low carb and training. I never did, my workouts suffered greatly when I was a on a full low carb diet atkins type, it would take me a lot more time to recuperate, the lactic acid build up was terrible etc.

    I get better results when I use a type of fasting like IF, I use coconut oil in pretty much everything cause it’s great for testosterone and so much more, I refuse to use steroids and drugs I never did and it’s not at 41 that I am gonna start, I use creatine mono with great results.

    But low carb for me is not my best option for optimal health.

    • Yannick,

      When working with low carb, it is great to lose both weight and body fat, however, as your weight drops, and you want to build muscle, you will find the lack of glycogen limits your muscle growth and abilities in the gym.

      It is fine to stay low carb on days that you do not lift, but you should back load carbs (after 8pm) the night before days that you do lift. It is great for some people, others find going 16 hrs (including sleep time) too much to handle.

      Also remember this… 58% of protein, and 10% of fat is converted into carbohydrates, so adding additional carbs is not mandatory… though most would say without it, it takes away from the enjoyment of food.

      If you were feeling weak on low carb, either re-feed one day per week, or back-load the night before workouts, and up your protein intake.

      • I love it, thank you very much and I will try this, trying to keep a low carb and refeed the night before a workout sounds very good.

        For the IF, if anyone is interested you don’t go 16 hours straight, you just take it easy and start slow, there is always the possibility to eat some type of fruit during the fast, I find that doing this brings the body back to its natural state, sugar urge is cut within a few days on it, you are less hungry and so many other benefits.

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