10 Disturbing Reasons Why Sugar is Bad For You

Woman Craving a DoughnutAdded sugar is the single worst ingredient in the modern diet.

It can have harmful effects on metabolism and contribute to all sorts of diseases.

Here are 10 disturbing reasons why you should avoid added sugar like the plague.

1. Added Sugar Contains No Essential Nutrients and is Bad For Your Teeth

You’ve probably heard this a million times before… but it’s worth repeating.

Added sugars (like sucrose and high fructose corn syrup) contain a whole bunch of calories with NO essential nutrients.

For this reason, they are called “empty” calories.

There are no proteins, essential fats, vitamins or minerals in sugar… just pure energy.

When people eat up to 10-20% of calories as sugar (or more), this can become a major problem and contribute to nutrient deficiencies.

Sugar is also very bad for the teeth, because it provides easily digestible energy for the bad bacteria in the mouth (1).

Bottom Line: Sugar contains a lot of calories, with no essential nutrients. It also causes tooth decay by feeding the harmful bacteria in the mouth.

2. Added Sugar is High in Fructose, Which Can Overload Your Liver

Glass Full Of Sugar Cubes

In order to understand what is so bad about sugar, then you need to understand what it is made of.

Before sugar enters the bloodstream from the digestive tract, it is broken down into two simple sugars… glucose and fructose.

  • Glucose is found in every living cell on the planet. If we don’t get it from the diet, our bodies produce it.
  • Fructose is different. Our bodies do not produce it in any significant amount and there is no physiological need for it.

The thing with fructose is that it can only be metabolized by the liver in any significant amounts.

This is not a problem if we eat a little bit (such as from fruit) or we just finished an exercise session. In this case, the fructose will be turned into glycogen and stored in the liver until we need it (3).

However, if the liver is full of glycogen (much more common), eating a lot of fructose overloads the liver, forcing it to turn the fructose into fat (4).

When repeatedly eating large amounts of sugar, this process can lead to fatty liver and all sorts of serious problems (5).

Keep in mind that all of this does NOT apply to fruit. It is almost impossible to overeat fructose by eating fruit.

There is also massive individual variability here. People who are healthy and active can tolerate more sugar than people who are inactive and eat a Western, high-carb, high-calorie diet.

Bottom Line: For people who are inactive and eat a Western diet, large amounts of fructose from added sugars get turned into fat in the liver.

3. Overloading The Liver With Fructose Can Cause Non-Alcoholic Fatty Liver Disease

Junk Food

When fructose get turned into fat in the liver, it is shipped out as VLDL cholesterol particles.

However, not all of the fat gets out, some of it can lodge in the liver.

This can lead to Non-Alcoholic Fatty Liver Disease (NAFLD), a growing problem in Western countries that is strongly associated with metabolic diseases (6).

Studies show that individuals with fatty liver consume up to 2-3 times as much fructose as the average person (7, 8).

Bottom Line: Excess fructose gets turned into fat, which can lodge in the liver and cause non-alcoholic fatty liver disease.

4. Sugar Can Cause Insulin Resistance, a Stepping Stone Towards Metabolic Syndrome and Diabetes

Doctor Thumbs Down

Insulin is a very important hormone in the body.

It allows glucose (blood sugar) to enter cells from the bloodstream and tells the cells to start burning glucose instead of fat.

Having too much glucose in the blood is highly toxic and one of the reasons for complications of diabetes, like blindness.

One feature of the metabolic dysfunction that is caused by the Western diet, is that insulin stops working as it should. The cells become “resistant” to it.

This is also known as insulin resistance, which is believed to be a leading driver of many diseases… including metabolic syndrome, obesity, cardiovascular disease and especially type II diabetes (9).

Many studies show that sugar consumption is associated with insulin resistance, especially when it is consumed in large amounts (10, 11).

Bottom Line: When people eat a lot of sugar, it can cause resistance to the hormone insulin, which can contribute to many diseases.

5. The Insulin Resistance Can Progress to Type II Diabetes

Diabetic Shooting Insulin

When our cells become resistant to the effects of insulin, the beta cells in our pancreas make more of it.

This is crucial, because chronically elevated blood sugars can cause severe harm.

Eventually, as insulin resistance becomes progressively worse, the pancreas can’t keep up with the demand of producing enough insulin to keep blood sugar levels down.

At this point, blood sugar levels skyrocket and a diagnosis of type II diabetes is made.

Given that sugar can cause insulin resistance, it is not surprising to see that people who drink sugar-sweetened beverages have up to an 83% higher risk of Type II diabetes (12, 13).

Bottom Line: Because of the harmful effects of sugar on the function of insulin, it is a leading driver of type II diabetes.

6. Sugar Can Give You Cancer


Cancer is one of the leading causes of death worldwide and is characterized by uncontrolled growth and multiplication of cells.

Insulin is one of the key hormones in regulating this sort of growth.

For this reason, many scientists believe that having constantly elevated insulin levels (a consequence of sugar consumption) can contribute to cancer (14).

In addition, the metabolic problems associated with sugar consumption are a known driver of inflammation, another potential cause of cancer (15).

Multiple studies show that people who eat a lot of sugar are at a much higher risk of getting cancer (16, 17, 18).

Bottom Line: There is considerable evidence that sugar, due to its harmful effects on metabolism, can contribute to cancer.

7. Due to its Effects on Hormones and the Brain, Sugar has Unique Fat-Promoting Effects

Boy Eating Ice Cream

Not all calories are created equal.

Different foods can have different effects on our brains and the hormones that control food intake (19).

Studies show that fructose doesn’t have the same kind of effect on satiety as glucose.

In one study, people drank either a fructose-sweetened drink or a glucose-sweetened drink.

Afterwards, the fructose drinkers had much less activity in the satiety centers of the brain and felt hungrier (20).

There is also a study where fructose didn’t lower the hunger hormone ghrelin nearly as much as glucose did (21).

Over time, because the calories from sugar aren’t as fulfilling, this can translate into an increased calorie intake.

Bottom Line: Fructose doesn’t cause satiety in the brain or lower the hunger hormone ghrelin nearly as much as glucose.

8. Because it Causes Massive Dopamine Release in The Brain, Sugar is Highly Addictive

Sugar can be addictive for a lot of people.

Like abusive drugs, sugar causes a release of dopamine in the reward center of the brain (22).

Woman Snorting Doughnuts

The problem with sugar and many junk foods is that they can cause massive dopamine release… much more than we were ever exposed to from foods found in nature (23).

For this reason, people who have a susceptibility to addiction can become strongly addicted to sugar and other junk foods (24).

The “everything in moderation” message may be a bad idea for people who are addicted to junk food… because the only thing that works for true addiction is abstinence.

Bottom Line: Because sugar causes a large release of dopamine in the brain, it can cause addiction in a lot of people.

9. Sugar is a Leading Contributor to Obesity in Both Children and Adults

Obese Man on a Scale, Smaller

The way sugar affects hormones and the brain is a recipe for fat gain disaster.

It leads to decreased satiety… and can get people addicted so that they lose control over their consumption.

Not surprisingly, people who consume the most sugar are by far the most likely to become overweight or obese. This applies to all age groups.

Many studies have examined the link between sugar consumption and obesity and found a strong statistical association (25).

The link is especially strong in children, where each daily serving of sugar-sweetened beverages is associated with a whopping 60% increased risk of obesity (26).

One of the most important things you can do if you need to lose weight is to significantly cut back on sugar consumption.

Bottom Line: Because of the effects of sugar on hormones and the brain, sugar dramatically increases the risk of becoming overweight or obese.

10. It Ain’t The Fat… It’s SUGAR That Raises Your Cholesterol and Gives You Heart Disease

Sugar cubes

For many decades, people have blamed saturated fat for heart disease… which is the #1 killer in the world.

However… new studies are showing that saturated fat is harmless (27, 28).

The evidence is mounting that sugar, NOT fat, may be one of the leading drivers of heart disease via the harmful effects of fructose on metabolism (29).

Studies show that large amounts of fructose can raise triglycerides, small, dense LDL and oxidized LDL (very, very bad), raise blood glucose and insulin levels and increase abdominal obesity… in as little as 10 weeks (30).

These are all major risk factors for heart disease.

Not surprisingly, many observational studies find a strong statistical association between sugar consumption and the risk of heart disease (31, 32, 33).

Take Home Message

For people who can’t tolerate it, added sugar is incredibly harmful.

Empty calories are just the tip of the iceberg.


  1. Thanks for the new article! I will be avoiding added sugars for now on.

    Was wondering though, is there any specific amount of fruit I should limit myself to? I don’t currently have weight problems and I eat 3-4 servings of fruit a day, is that too much?

  2. Nice summary. A print-friendly version would be handy. I could pin it to the Social Club fridge at work!

  3. “Added sugar is the single worst ingredient in the modern diet.”

    What a brilliant first line Kris. A good friend of mine calls sugar ‘the menace in modern society, modern living’. Have to say I agree.

    I think if we can cut down sugar intake especially among the younger population so they do not get used to or addicted to the taste, it can only help.

    The trouble is sugar/fructose is everywhere now. Making people more aware of the damage it does must surely help. Of course the final choice as to whether you reduce sugar intake is still up to the individual, but I know what my choice is. Added sugar should perhaps have a ‘skull and cross bones’ sign next to it… Just a thought!

    All the best, Jan.

  4. Thank you. Great article. I’d also appreciate some information about artificial sweeteners. It’s my understanding that they’re worse than sugar but this article doesn’t mention them. I worry that people will think they just need to swap sugar for the artificial stuff. And what about honey, guava syrup, coconut sugar and stevia? Better? Worse? Or just as bad?

    • Meg, Stevia is a natural sweetner. I’m a Master Gardener and I grow it in my garden. Just one leaf of it in my tea is plenty of sweetness. Some say that it has an after taste but I don’t notice it. I’d rather have stevia than sugar.

      As for information on artificial sweeteners and additives, I agree, they are very bad for you too! You have to be careful of all of it. Take a look at: “Top 10 Food Additives to Avoid – Food Matters”, Google it. This is a very good chart that I found a while back.

  5. So many people in the world still don’t understand this and look towards fat as the culprit of many of these issues.

  6. At least 30 years ago a Chiropractor mentioned from Halloween to Easter was our “sick” time, referring to colds and flu. He stated temperature changes, being indoors, spreading germs, etc had a small play in the cold and flu season, but placed much more emphasis on Halloween candy, Thanksgiving desserts, Christmas treats, Valentine chocolate, and Easter candy. Sugar associated with each major holiday celebrated in the US. He was definitely on target.

  7. 1. Added Sugar Contains No Essential Nutrients and is Bad For Your Teeth
    4. Sugar Can Cause Insulin Resistance, a Stepping Stone Towards Metabolic Syndrome and Diabetes
    5. The Insulin Resistance Can Progress to Type II Diabetes
    6. Sugar Can Give You Cancer
    10. It Ain’t The Fat… It’s SUGAR That Raises Your Cholesterol and Gives You Heart Disease

    These five reasons, at least, are all true also for grains. The starches in grains are nothing but chains of glucose molecules, and they’re metabolized as quickly as sugar. The glycemic index of a bagel is as high as that of a candy bar. So merely eliminating added sugar isn’t enough–you have to limit grains, too.

    • True, but a little misleading. Corn has 70% starch, but oats have 45% starch and a lot of fiber, such as beta-glucans, which are healthy. Also, oats have a globular protein structure (very different from gluten) and relatively high protein levels for a grain. So, demonizing all grains is bad advice, too.

      • Dear Dave A, thank you so much for your clarification, it was helpful.

      • I’m not demonizing all grains, just pointing out that they’re basically just sugar–OK, with some protein, fiber, fat, and trace minerals, but starch (sugar) dominates.

        Beta glucans are good but there are ways to get them that don’t spike your blood sugar like oats.

        Also, oats are about 60% starch, not 45%.

        • I think 60% is too high, but I also think that I was looking at data from oats with the hull still on.

          From Bach Knudsen (1997) Anim. Feed Sci. Tech. 67:319

          Hulled oats (n=3) – 46.8% starch +/- 2.5%
          Dehulled oats (n=4) – 55.7% starch +/- 3.8%
          Corn (n=3) – 69% starch +/- 1.8%

          What I do, I think, would reduce the blood sugar spike. I cook rolled oats for only a few minutes (not five, like the label says) so they are still crunchy (and less digestible), and I sprinkle a little whey protein on them (no sugar).

          So, processing and preparation before consumption matter a lot, too. Good discussion…

  8. Wenchypoo says:

    Speaking of addicting, aren’t sugar and cocaine just an atom arrangement away from each other–something like only three atoms’ difference?

  9. Hello Kris. I’ve been off sugar for about four months now and all high carb foods for about two months, with the exception of a small gluten-free brownie I had to eat recently while travelling (thanks to bad planning on my part). The brownie tasted so sweet it was almost painful to eat. It occurred to me later that the absence of sugar in my diet for four months may have changed my sense of taste. In fact, I’ve also noticed that I taste and enjoy the flavours of whole foods more now.

    This got me wondering, does sugar (or carbs in general), have some physiological impact on the brain’s mechanism for translating taste sensory input into satiety) and if so, is this a factor in modern Western obesity, ie are carbs numbing to the amount we’re actually eating? Do you know of any research addressing this?

  10. Good post on a “story” that obviously needs to be told and re-told. Melvin Page, DDS measured several deleterious effects of sugar on blood chemistry back in the 1930s and 40s. When the AMA took him to court in the 1960s, Dr. Page was able to substantiate his anti-sugar claims with 3,600 case studies and over 40,000 lab results.

  11. I recently started to use coconut sugar (should not be confused with palm sugar) instead. The glycemic index of coconut sugar is 35, so it is better than white sugar or brown sugar.

  12. Debbie Parker says:

    There is no doubt at all that sugar is literally “sweet poison”. It took me about a month to get my daily sugar intake to a sensible level and was constantly shocked about how many foods had hidden sugar – fruit juice being one of the worst. Some studies on rats have shown that sugar is more addictive than cocaine!

  13. Great post! Thanks.

    Just discovered your web page and I’m impressed, congratulations. A lot of theories I support translated into evidences.


  14. The article left out one important thing: sugar breaks down collagen and makes people age faster.

  15. I notice that every image in this article is high fat (donuts, chips, cookies, Twinkies, muffins, ice cream). Just saying.

  16. I enjoyed reading this and the following comments. I was brought up with a lot of sugar consumption and experienced 20 years of bad eczema and when seeking health care through a naturopath I did an elimination diet along with tests and I am sugar intolerant, big time!

    It has been a good force to kick the pull of the sweet tooth and there’s plenty of other recipes out there. It has encouraged my creativity a lot more in the kitchen and I don’t desire it as much anymore because it isn’t in my system. Sugar is not worth your health.

  17. Ayodigi Burse says:

    You forgot something.

    Sugar cane, corn are GRAINS that cause inflammation of the tissues and destruction of nerves.

    • Thanks Ayodigi. I didn’t know sugar cane was a grass! The connection between ‘neocarbs’ and autoimmune disease is the thing that interests me most about a low carb lifestyle.

      • Forgot about the grass versus grains stuff. Corn is a grass, too. If you refine sugar from any source, it will be rapidly absorbed, spike in your blood, and cause insulin to spike in response. Then, it will be quickly metabolized, and sugar levels in blood will crash (and insulin will follow). Hunger will follow. This is the problem, not the grass versus grain idea. Raw sugar eaten with fat and protein will slow this boom-bust sugar cycle. Or, cutting back on sugar altogether.

  18. It is very good to know that what we eat that is delicious will eventually kill us! Ha! Of course I am very aware of the damage sugar is causing, putting on weight alone is a let down already!

    So I’m choosing the tasteless version of most foods, eating less fruits which are sweet, and advise family and friends to do the same! Have a great life, without sugar :(

    • This article is not about fruit, it is about added sugars like sucrose and high fructose corn syrup.

      Fruit can be a part of a healthy diet: http://authoritynutrition.com/is-fruit-good-or-bad-for-your-health/

      Also… eating healthy does NOT have to taste bad. I enjoy every single one of my meals.

      • Hi Kris,
        I gave up sugar 1 year ago, it was the best thing I have done. I never gave up fruit, as I have fruit for breakfast. It was the hidden sugars that was the biggest problem. I make my own muffins but instead of sugar I put 2 bananas in the recipe, that way I get a treat. It is difficult when sugar is everywhere, but you can cut down such a lot by just keeping an eye on what you buy. Keep up the good work. Thank you.

  19. All these health freaks are talking like they are specialists or doctors. Sugar is good to eat if you keep it in moderation, brown sugar or sugar cane is good for you. Don’t just listen to these freaks and get paranoid about what to eat. There isn’t any proof that drinking coke is bad. IMHO, cancer is caused by stress and an unbalanced diet.

  20. Thanks for the nice article! Unfortunately the ADA still sets us up for failure with a 1200 – 1550 calorie (semi-starvation) low-FAT diet and tells that we can still have candy, white flour, sugar, cookies, etc; as part of “our meal plan”; Sugar is killing us; but they scream of fat while forgiving sugar (and pushing drugs) (scam???).

    I was size 16 (pants getting tight); I got rid of cow-milk, candy, juice, white flour bread, white flour pasta, white rice, sugar, vegetable oil, soda, doritos, potato chips.

    I try to be active and I consume vegetables, berries, nuts, seeds, fruit, water, stevia extract, unsweetened fortified coconut milk, virgin coconut oil, eggs.

    I am not vegangelical; but not paleovangelical either; I avoid hot dogs and other processed meats like bologna, I go days or weeks at a time without meat.

    I am NOT a fat phobe; and use unsweetened bakers chocolate as an alertness aid.

    I got rid of the rigid prisonlike 3-meal a day thing that gave me such anxiety, fear, anger, helplessness; I eat when hungry; stop when full.

    My pants are now size 6. I am much more calm about food. My sugar is better. I do not buy sugar and avoid sugary treats, tell people sugar is a problem for me!

    I feel free.

  21. The “everything in moderation” message may be a bad idea for people who are addicted to junk food… because the only thing that works for true addiction is abstinence. So true for you… how true! After going sabbatical on sugar for 2-3 days, I will start with a ‘bit’ of sweet and end up eating loads of them. Eye opener indeed!

  22. Bharat Jain says:

    We generally overlook the danger posed by refined sugar. It is high time a sustained campaign was launched against added sugar.

    So take a vow to enlighten others about the unacknowledged danger.

    Start now.

  23. I just found this site and it is a WONDERFUL easy-to-understand resource, thank you! Can you just clarify for me – so all added sugars contain fructose, yes?

  24. Franklyn Crowe says:

    Good article. I am now learning more about sugar and came accross this article. It will be a tough climb but I will get rid of sugar from my system.

  25. Sharon Leng says:

    On ” However… ‘new studies’ are showing that saturated fat is harmless (27, 28), check out:

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