Mythbusting: Does Fructose Cause Obesity?

Myth: Fructose is worse for you than table sugar.

Fact: Neither fructose nor table sugar is inherently harmful— it’s all about moderation and balancing your overall diet and activity level.

There are many reasons why people become obese and unhealthy.  One blame target is fructose and other forms of refined sugars.  In blogs and Google searches, fructose has gotten a reputation of contributing to obesity.

Why would fructose be singled out? Along with glucose, fructose makes up 50% of table sugar, after all. In fact, we rarely if ever eat fructose without glucose. Natural sources of fructose and glucose include fruits, some vegetables, honey, sugar cane, and sugar beets. Because it is a component of sweeteners such as sucrose and high fructose corn syrup, fructose is present in a wide range of sweetened foods and beverages.fruits-with-fructose

Even though each type of sugar provides basically the same number of calories, they are metabolized and used by the body in different ways. Glucose is digested, absorbed, transported to the liver, and released into the general blood stream. Many tissues take up glucose for energy, which requires insulin.

Fructose is predominantly metabolized in the liver, so it doesn’t require insulin to be used. Because of that difference, fructose doesn’t stimulate some body responses that could help to regulate hunger (insulin and leptin secretion and ghrelin production). For these reasons, some researchers have speculated that fructose may not make you feel full the same way that other carbohydrates do. However, these suspicions are largely based on preliminary research involving unrealistic doses of fructose. Additionally, fructose is not really consumed in isolation from glucose. There is no evidence for such effects in humans consuming moderate amounts of fructose (~ < 50g / day) (Rizkalla, 2010).

A systematic review by Sievenpiper et al. (2012) found similar results, concluding that fructose is a red herring in the quest to pinpoint the cause of obesity. Excess calorie intake is the real, less sensationalistic culprit.

Excess body fat results when people do not balance their energy (caloric) input with energy output. Extra calories may come from any caloric nutrient—proteins, fats, alcohol and carbohydrates including starches and sugars such as fructose. Lack of physical activity plays a significant role in promoting body fat accumulation and development of obesity.

All sugars, including fructose, can be included in a healthful diet if eaten in moderation.

Learn more about fructose

This blog post was authored by Dennis Buckley, George Mason University intern.