Sugar sad face

What's Wrong with Sugar?

By wlr Contributor Dr Muhamad Usman MD

Dr Muhamad Usman sifts through the grains of evidence to find out how sugar affects your body, weight and health.

11 Reasons Why Sugar is a Sweet Poison

1. Sugar promotes weight gain

There are several reasons why sugar leads to weight gain.

First, a large proportion of the sugar in your daily diet is “added”. It means most of the sugar in average diets is added to processed foods to make them taste good. (Whilst adding no other nutritional value.)

Look around, almost every food ‘product’ has sugar in it - ketchup, sauces, soft drinks, biscuits, sweets, cakes, yoghurts, ready meals, even many ‘savoury’ snacks. It means you’re injecting a lot of extra calories into your system for no good reason.1

Another reason why simple sugars promote weight gain is due to their poor effect on your satiety levels. Complex carbs and protein are satiety promoting foods compared to simple sugars. A raft of clinical studies show that individuals who consume more added sugars end up eating more.2-5

Finally, one factor that determines the ability of a sugar to add to your weight is its Glycaemic Index (GI). Glycaemic index is the ability of a food to raise your blood glucose levels after you eat it. Simpler sugars, like table sugar, are among foods with high GI.

Research shows that high GI foods promote weight gain in two ways.

First, they are a lot less satisfying compared to lower GI foods. In one piece of research, teenage boys who were given high GI foods felt hungrier, and ate 53% more calories, than those who ate low GI foods.

Second, high GI foods promote an increase in the levels of insulin in your body and limit fat breakdown.

Research says that such foods may actually increase fat deposition.6-8

In fact, some forms of sugar, like fructose which is mainly found in fructose rich syrups/corn syrups, are largely converted into fat in the liver.9 Researchers believe that drinking just 1 sugary beverage every day increases your risk of gaining weight by 60%. 10

It’s important to note that we’re not talking about eating fruit here.

Fruit does contain naturally high levels of sugar, but when eaten in its whole state, the sugar is absorbed more slowly and fruit contains a wide range of important nutrients. Added sugars and table sugar have essentially no nutritional value other than the energy (calories) they provide.

There are a lot of clinical studies linking the consumption of sugar to weight gain, but one systemic review is worth mentioning here. In that review researchers evaluated almost all major studies done till date that show a link between sugar consumption and body weight. Here is what the results looked like:11

Sugar Promotes Weight Gain
Sugar Promotes Weight Gain
Study Design Total Number of Studies Studies with a Strong Positive Association Between Sugar Consumption and Weight Gain Studies with No or Negative Association Between Sugar Consumption and Weight Gain
Cross sectional 15 10 5
Cohort 10 7 3
Clinical Trials 5 5 0

It means that out of the 30 studies isolated, 23 found a positive relation between sugar consumption and weight gain.

2. It increases the risk of Type 2 Diabetes

It is a consistent finding that consuming sugars, like sucrose and fructose, significantly increases the risk of type 2 diabetes.

In a review, researchers examined results from 11 different studies with 310, 819 participants in total. The researchers concluded that individuals consuming more sugar were 26% more likely to develop type 2 diabetes.12

Insulin is responsible for the metabolism of sugars, except fructose. It is manufactured in the beta cells of your pancreas. There are two main reasons why long-term sugar intake increases your risk of developing type 2 diabetes.

First, according to the Korean National Institute of Health, chronic exposure to sugar is toxic for the beta cells of pancreas. It can cause the death of these cells and subsequently significant reduction in insulin secretion.13

The second, and more important reason, is an increase in insulin resistance. Insulin resistance means your cells do not respond properly to the insulin your body produces.14-15

The good news is that diabetes due to sugar consumption can be somewhat reversed.

In one trial, researchers studied the effects of sugar reduction on insulin levels in obese women. Results showed that the reduction of sugar intake to 10% of total daily calorie intake can cause a significant improvement in insulin secretion and sensitivity.16

3. Alzheimer’s is Another Bitter-Sweet Truth of Eating Sugar

The human brain is one of the most complex structures known. Unlike other parts of the body, which can use glucose, proteins and fats as sources of energy, your brain largely depends on glucose as an energy source.

Alzheimer’s is an age-related brain disorder. It is characterized by deterioration of structural and functional capacity of your brain. Researchers have unveiled a strong link between this condition, sugar intake and type 2 diabetes.

Researchers believe that insulin resistance compromises the supply of glucose to the brain. Sugar intake also promotes brain inflammation, which adds insult to the injury. Also, it accelerates the piling up of abnormal proteins in the brain, which is the hallmark of this condition. 17-20

4. Sugar has profound effects on your cardiovascular health

Triglycerides are chemicals in your blood. These chemicals are needed at a minimal level for several important functions. But when their levels rise, it increases the risk of conditions like high blood pressure, heart attack and stroke.

Researchers have now started to unravel the link between sugar intake and an increase in the level of these chemicals.

In one piece of research, scientists made an astounding discovery. They studied the effects of a high sugar, low fat diet and a low sugar, high fat diet on blood levels of triglycerides. Unexpectedly, they found no increase in the levels of triglycerides with the low sugar, high fat diet. But, with the high sugar, low fat diet, they recorded a significant increase in blood levels of triglycerides.21

In further research, scientists changed the sugar content of the diets of the participants and studied its effects on serum triglyceride levels. They found that the group who ate more sugar experienced 46% increase in their serum triglyceride levels compared to low sugar group that experienced only a 21% increase.22-23

An increase in the blood levels of these chemicals translates to an increased risk of conditions like high blood pressure.

A lot of clinical data supports the fact that use of sugar promotes hypertension.24 In one particular study, researchers found that drinking more than 1 sugary beverage every day can significantly increase the risk of developing high blood pressure in the longer run.25

Clinical data linking sugar consumption to more devastating outcomes like heart attack and stroke is scarce. But new research has started to come in that links high GI foods with an increased risk of heart attack and stroke.26-27

5. Sugar can throw your hormones off balance

Sugar messes with your hormones. Here is the detail of the hormones it affects and the subsequent consequences:

Affected Hormones Effect on the Body
Thyroid Hormone28 Hypothyroidism: Decrease in thyroid levels, which can lead to weight gain, slurred mentation, constipation, intolerance to cold and lethargy.


Hyperthyroidism: Increase in thyroid levels, which can lead to confusion, weight loss, diarrhoea, intolerance to heat and body aches.

Growth Hormone29 Long-term consumption of sugar and persistent increase in blood sugar levels can decrease growth hormone levels and impair growth in children.
Testosterone30 Only one time sugar intake can decrease testosterone levels by 25%. It can then lead to erectile dysfunction, poor libido and infertility.
Oestrogen31 Excess sugar can cause oestrogen imbalance in females, which can lead to Polycystic Ovarian Syndrome (PCOS). PCOS leads to menstrual abnormalities and infertility.
Insulin Type 2 diabetes

6. Sugar can increase toxicity levels in your liver

Sugars, especially fructose, go hard on your liver. Fructose is primarily metabolized in your liver. When you eat fructose, it makes its way to your liver. In your liver, unlike other sugars, it is turned into fat instead of being used as energy. This way, it increases the total amount of fat in your liver.

Researchers have studied the effects of the intake of fructose on fat deposition in the body. They have found that fructose increases the fat deposits in your body, specifically in your liver and the muscles. The piling up of fat in the liver is called non-alcoholic fatty liver disease. 32-33

Non-alcoholic fatty liver disease is the first stage of liver failure. If it continues, you can end-up with fulminant liver failure, which can be life threatening.

Sugar Rots Teeth
Sugar Rots Your Teeth

7. Sugar Rots Your Teeth

You might remember your mom or grandma stopping you from eating sweets. You might have hated it back then but it was for your own good. A lot of bacteria in your mouth thrive on the sugar you eat. They ferment the sugar into an acid, which then destroys the enamel of your teeth- the hard outer covering of your teeth. This is when you get dental caries. 34

8. Cancer Risk

But, that’s not it. Sugar does more harm to your body than just giving you innocuous dental caries. Newer research now suggests that excessive sugar intake can significantly increase the risk of different kinds of cancer, like pancreatic and small intestine cancer. Scientists blame the ability of sugar to meddle with insulin levels for this effect.35-36

Sugar Hides in Drinks
Sugar Hides in Drinks

9. Sugar Hides in Drinks

The satiety properties of a food depend on its form i.e. whether it is solid or liquid.

There has been a drastic shift in our eating patterns over the last few decades, but the one most significant change is the advent of sugary beverages and soft drinks.

Researchers believe that you are more likely to gain weight after drinking sugary beverages than eating similar solid foods. That’s mainly because beverages have a poor potential of provoking satiety.37-39

In one study, 15 adult subjects were given 450 Kcal in the form of sugary beverages or solid foods (jelly). The results were evaluated after 4 weeks. Researchers found that the group drinking fluids experienced a 17% increase in their daily caloric intake and significant increase in weight compared to the solid food group.37

The bottom line is that sugar- whether it is in solid or liquid form- can cause weight gain. But, you’re more likely to gain weight after drinking sugary beverages than eating solid foods with similar sugar content.

10. It’s a Growing Addiction

Experts have seen a 22-fold increase in the consumption of sugar among the UK population over the last one century. It is difficult to quantify the total amount of sugar an average British citizen consumes because almost every edible item contains a sugar in some form. Some estimates suggest that an average UK resident may be consuming up to 90 grams (or 22 teaspoons) sugar daily.40-41

There is a bit of conflict about what constitutes a safe daily sugar intake amongst various health authorities. But, according to the most recent recommendations by the World Health Organization (WHO), the daily intake of added sugars should not exceed 10% of total daily calorie intake (or 12 teaspoons).42

The WHO further say that reducing sugar intake to 5% of daily calories (or 6 teaspoons) can have additional health benefits.42

The bottom line is that your target should be consuming not more than 12 teaspoons (or less) of added sugars on daily basis.

Sugar is Addictive
Sugar is Addictive

11. We’re Programmed to Like It

Cravings for sugar are real. Even just reading the word “sugar” may flood your brain with neurotransmitters and increase your saliva production. According to research, cravings for sugar share the same area of your brain as does sex- the strongest of all desires.43

The question is; do you acquire a sweet tooth or is it something encoded deep in your genes? While what you eat is strongly affected by your personal preference, a love for sugar grows in you even before you are born. In fact, researchers now believe that a “sweet tooth” played a critical role in human evolution.44 Our ancestors knew that whatever tastes sweet must be good for them. This marks the genesis of our love for sugar.

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  31. Relation of nutrients and hormones in polycystic ovary syndrome
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  40. Britain is built on sugar
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  44. The Human Sweet Tooth

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