In the beginning, the conventional low-fat diet was based on very weak scientific evidence, which has since been thoroughly disproven.
In the past few decades, many massive, long-term studies have shown that this diet is a very poor choice.
Not only is it proven to be ineffective, it can also be downright harmful for a lot of people.
Here are 7 ways the low-fat diet can harm your health.
1. The Low-Fat Diet Encourages Consumption of Harmful Foods
When the low-fat guidelines first came out, food manufacturers jumped on the bandwagon.
They wanted to bring a whole bunch of “heart healthy” low-fat foods to the market, in order to sell to the health conscious crowd.
However, there is one big problem with foods that have had the fat removed from them… they taste like crap.
For this reason, the food manufacturers added sugar instead. Sugar is not a fat, it’s a carbohydrate. Therefore, a product can be labelled “low fat” even though it is loaded with sugar.
(I should point out that the low-fat guidelines DO recommend that we reduce refined sugars, but not nearly as enthusiastically as they warn us about the “dangerous” fats).
The conventional low-fat diet (brought to you by the United States Department of Agriculture) also advocates increased consumption of certain foods:
- Vegetable Oils: Vegetable oils can reduce cholesterol in the short term, but in the long term they cause harm and are significantly associated with inflammation and heart disease (1, 2, 3, 4, 5).
- Whole Wheat: A significant portion of the population may be sensitive to wheat gluten, experiencing symptoms like pain, stool inconsistency, tiredness, among various other symptoms (6, 7, 8, 9, 10).
Basically, since the low-fat guidelines came out, people have increased their consumption of harmful foods like sugar, wheat and vegetable oils.
Bottom Line: Many high sugar junk foods with a low-fat label have flooded the market. The low-fat diet also advocates consumption of foods now known to cause harm.
2. The Low-Fat Diet Can Raise Your Triglycerides
Having elevated triglycerides in the blood is a well known risk factor for cardiovascular disease.
It is also one of the features of the metabolic syndrome, a cluster of symptoms believed to play a causal role in cardiovascular disease, obesity and type II diabetes.
Bottom Line: The low-fat diet is very high in carbohydrates. Excess carbohydrates are turned into fats in the liver, which raise blood levels of triglycerides, an important cardiovascular risk factor.
3. The Low-Fat Diet Discourages Consumption of Healthy Foods
Animal foods that are naturally high in fat tend to be healthy and nutritious.
While I agree that factory farmed, grain-fed animal products aren’t an optimal choice, foods from animals that have been properly raised and fed are very healthy.
The low-fat diet discourages people from consuming these foods because they contain saturated fat and cholesterol.
Here’s a newsflash: Neither saturated fat or cholesterol have ever been proven to cause harm.
Blaming the epidemics of obesity, diabetes or heart disease on fatty animal foods makes absolutely no sense, because the diseases are relatively new, while the foods have been with us all along.
Plenty of populations throughout the world, for example the Inuit and the Masai, have consumed almost all of their calories from animal foods and remained in excellent health.
- Meat: Naturally fed meat is an excellent source of Omega-3 fatty acids, CLA, vitamins and minerals along with important nutrients like Carnosine and Creatine (24, 25, 26).
- Eggs: Eggs are among the healthiest foods on the planet. They are loaded with vitamins and minerals, along with Choline and powerful antioxidants that protect the eyes (27, 28).
- High-fat dairy products: Grass-fed dairy products are the best source of Vitamin K2 in the diet. Also loaded with Calcium, CLA and plenty of other nutrients (29, 30, 31).
- Coconut: Coconut products contain fats that are associated with powerful health benefits, including increased fat burning, better blood lipids and improved brain function (32, 33, 34).
Bottom Line: Foods that are naturally high in saturated fat and cholesterol tend to be highly nutritious and perfectly healthy. The low-fat diet discourages consumption of these foods.
4. The Low-Fat Diet Can Lower HDL (The “Good”) Cholesterol
High Density Lipoprotein (HDL) is often referred to as the “good” cholesterol.
Bottom Line: HDL is known as the “good” cholesterol and is associated with a reduced risk of heart disease. Studies show that the low-fat diet reduces blood levels of HDL.
5. The Low-Fat Diet Lowers Testosterone Levels
Testosterone is the main sex hormone in males, but women have small amounts of it too.
Like other steroid hormones, testosterone is produced out of cholesterol.
Having adequate testosterone levels is important for various aspects of health in both men and women.
Having low testosterone levels can lead to decreased muscle mass, increased body fat, osteoporosis, depression, decreased libido, among others.
Bottom Line: Testosterone is a very important hormone in both men and women. Low-fat diets can significantly reduce testosterone levels.
6. The Low-Fat Diet Can Harm The Pattern of LDL (The “Bad”) Cholesterol
Low-Density Lipoprotein (LDL) is often referred to as the “bad” cholesterol.
It is well established that elevated LDL levels are associated with an increased risk of cardiovascular disease (47).
However, new data is showing that there are subtypes of LDL. We have small, dense LDL (called pattern B) and Large LDL (called pattern A).
A high intake of carbohydrates (especially refined carbohydrates) increases sdLDL, while saturated fat and cholesterol change the LDL particles from the small, dense (bad) subtype to the large (benign) subtype (51, 52, 53).
Bottom Line: Even though low-fat diets may cause mild reductions in LDL cholesterol, at the same time they shift the pattern of LDL cholesterol from Large LDL (which is benign) towards small, dense LDL (which is very harmful).
7. The Low-Fat Diet Gives You Heart Disease
Heart disease is the most common cause of death in middle- and high income countries (58).
When these populations adopt a western diet, they rapidly become obese, diabetic and start dying from heart disease (62).
Therefore, it seems pretty clear that the western diet is a significant contributor.
There have been several massive, long-term randomized controlled trials (which are the gold standard of science) that have examined the effects of low-fat diets on the risk of heart disease.
- The Women’s Health Initiative: In a study of 48,835 women, the low-fat diet produced weight loss of only 0.4 kg (1 lb) over a period of 7.5 years. The diet did not lower the risk of heart disease or cancer (63, 64, 65, 66).
- MRFIT: A low-fat diet did not reduce heart disease in a group of 12,866 men at a high risk of having a heart attack, despite the fact that many of the men quit smoking (67).
- Look AHEAD: A 9.6 year study of 5,145 diabetics revealed that the low-fat diet did not reduce heart disease, despite the fact that they managed to lose weight by forced calorie restriction (68, 69).
Be aware that they are comparing the low-fat diet to the standard western diet, which is pretty much as bad as a diet can get.
Another way to consider these results… The low-fat diet is just as effective at causing heart disease as the standard Western diet.