Researchers Suggest Fructose Is Central Factor Causing Obesity

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Oct. 20, 2023 – Obesity researchers have struggled to pinpoint the cause of the illness. They have observed links between obesity and genetics, diabetes, caloric intake, high fat foods, and carbohydrates. Now, a new theory suggests that all of those factors matter, but the key driver of obesity may be fructose. 

Fructose is present in small quantities in foods such as fruits, and in large quantities in sweeteners like table sugar and high fructose corn syrup. In a scientific article published this week in the journal Obesity, researchers explained that fructose triggers cravings for fatty foods and carbohydrates, while blocking the body’s ability to use stored energy from fat. 

Ultimately, fructose drives people to eat more food that then is stored as fat, in a cycle that continues to block the body from using that stored energy while telling it to acquire more. When observed in other mammals in nature, the cycle is typically triggered in times of crisis. The researchers called it “a spectacular system that prepares animals for a time when food, water, or oxygen are less plentiful, such as in preparation for long distance migration or hibernation.”

The body can also make fructose instead of getting it from dietary sources. In addition to the fructose cycle triggered in times of stress, it can stem from having excessive glucose, which occurs with diabetes, the researchers noted, and when consuming a diet high in salt or low in water. 

The authors explained that eating fruit is unlikely to trigger the problematic fructose cycle because fruit contains low levels of fructose and the nutrient and fiber in fruit can neutralize fructose’s effects. But alcohol, particularly beer, results in the body generating fructose, they noted.

“Essentially, these theories, which put a litany of metabolic and dietary drivers at the center of the obesity epidemic, are all pieces of a puzzle unified by one last piece: fructose,” said author Richard Johnson, MD, a researcher at the University of Colorado Anschutz Medical Campus, in a news release. “Fructose is what triggers our metabolism to go into low power mode and lose our control of appetite, but fatty foods become the major source of calories that drive weight gain.”