Why is Sugar Harmful?

Posted on November 29, 2014 · Posted in Blog, General, Personal

Sugar cubes

When discussing the health effects of sugar, it is important to realize that sugar isn’t like any other carbohydrate.

Most carbohydrate foods like bread, rice and potatoes contain starches, which are polymers of the monosaccharide glucose.

Glucose is part of the metabolism of every cell on the planet. Without it, life would not be possible. If humans don’t get any glucose from the diet, they produce it.

However, the added sugars in the diet, mainly sucrose and high fructose corn syrup, contain both glucose AND fructose.

Fructose is very different from glucose, because it is metabolized almost exclusively by the liver.

When the liver is already full of glycogen and becomes overloaded with fructose, it turns a large part of it into fat. This fat can lodge in the liver and cause insulin resistance, leading to elevated insulin levels all over the body (1, 2, 3).

People who are lean, active and metabolically healthy can afford to eat some added sugars without it having any harmful effects on metabolism.

However, they do appear to cause harm for a lot of people. In the context of inactivity and excess calories, eating a lot of sugar can cause severe metabolic problems (4).

In rats, a high fructose diet is often used to induce metabolic syndrome, which dramatically raises the risk of obesity, type II diabetes and heart disease (5, 6).

Fructose Causes Harmful Effects That go Way Beyond Empty Calories

Glass Full Of Sugar Cubes

A study by Kimber Stanhope, one of the scientists interviewed in the 60 minutes feature, revealed that the calories from fructose aren’t like other calories.

In her study, healthy individuals were randomized to consume either glucose-sweetened or fructose-sweetened drinks.

The calories in the groups were exactly the same, the only difference was that one group got 25% of calories from a glucose drink, the other 25% from a fructose drink.

After a 10 week study period, the fructose group had (7):

  • Increases in small, dense LDL, apoB and oxidized LDL, indicating an increase in the risk for cardiovascular disease.
  • Increased insulin resistance, the hallmark of metabolic syndrome.
  • Increased fat in the abdominal cavity, the visceral fat that is highly associated with metabolic disease.
  • Increased blood sugar and insulin levels.

Of course, the fructose dose in this study was fairly large (25% of calories) but the effect it caused was very dramatic and quick.

It is quite likely that a lower intake of sugar, consumed over a longer time period (many years) could have the same harmful effects.

Sugar, Insulin and Cancer

Another expert interviewed in the video, Lewis Cantley, has done research on the effects of insulin on tumor growth.

According to him, elevated insulin levels caused by excess sugar consumption could be fuelling a large increase in certain types of cancers, including breast and colon cancer.

There are several papers and observational studies supporting this link between sugar intake and various form of cancer (8, 9, 10, 11, 12).

Sugar is Addictive

Woman With Sugar on Her Lips

According to neuroscientist Eric Styce, another expert interviewed in the 60 minutes feature, sugar can be addictive.

He has used MRI scans to evaluate what happens in the brain when people eat sugar.

He discovered that sugar causes stimulation of the reward centers in the brain in a similar manner as drugs of abuse like cocaine.

This is consistent with studies on rats, showing that sugar causes many of the same effects (13).

This rewarding effect is blunted in obese individuals, which means that they have to consume even more sugar to reach the same effect.

I am personally convinced that sugar is addictive. It shares many of the same features as drugs of abuse. People start binging on it, they crave it obsessively and lose control over their consumption.

Their brain becomes dependant on the dopamine releasing effects of the sugar (and other junk foods) they are eating, leading to full-blown addiction (14).

This may be one of the main reasons that it can be so hard for some people to eat healthy and lose weight, they tend to “relapse” back into their old eating habits.

Take Home Message

This only applies to added sugars, NOT moderate consumption of fruits, which are real foods with fiber, water and a low energy density.

Fruits are almost impossible to overeat on, except perhaps for those who are diabetic or very carb sensitive. Fruit juice is an exception and should be avoided. It contains just as much sugar as a sugar-sweetened beverage.

Also be aware that “healthier” sugars like agave and organic cane sugar are just as bad as regular sugar.

In my opinion, the single most important change anyone can make to their diet is to cut back on added sugars. -authoritynutrition.com

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