Why Fructose Is Making Us Fatter

From 1977 to 2001, this country's consumption of sweetened beverages containing fructose increased 135%. Many researchers suspect that this statistic doesn't just relate to higher supermarket sales but also links directly to the national obesity epidemic. Fructose is found in high fructose corn syrup, a common ingredient in beverages as well as processed foods, which is produced from cornstarch and contains glucose and fructose. According to the USDA Economic Research Service, one reason high fructose corn syrup is widely used is that it is less expensive than sugar (sucrose) so manufacturers can save money -- especially in foods and beverages on the lower end of the price spectrum. However, research presented at a 2007 conference of the American Diabetes Association makes it seem that fructose isn't actually such a bargain in terms of health.

This study focused on measurable weight gain from swapping forms of sugar and was conducted at the University of California, Davis. Two groups of overweight and obese adults were instructed to eat as they usually did, and also to drink three special sweetened beverages per day, provided by the researchers. Half the group drank beverages sweetened with glucose. The other group was given beverages that had the same number of calories, but were sweetened with fructose.


In the end, neither group reduced calories to make room for the beverage calories, I was told by Kimber Stanhope, MS, RD, lead author of the study. Instead most ate more, she said. Additionally, she told me "the fructose subjects gained intra-abdominal fat (in the area around the abdominal cavity), whereas the glucose subjects did not." This is an important distinction, because intra-abdominal fat -- the kind that settles in your middle -- is associated with metabolic syndrome, which increases the risk of diabetes, heart disease or both.

Yet more bad news was delivered when researchers measured triglycerides, a kind of fat found throughout the blood stream and long recognized as an independent risk factor for heart disease. In previous human studies on fructose, researchers had measured fasting triglycerides and it didn't seem to have much effect. But in this study, researchers measured triglycerides after eating -- called a post-prandial measurement. It turned out that fructose doubled the levels of post-prandial triglycerides (compared with the glucose group) whereas glucose brought about a decrease, Stanhope said.

It appears, therefore, that fructose consumption not only has the potential to cause weight gain but also over-consumption may increase risk factors for atherosclerosis. "Within just two weeks, the overweight men and women in the study who were assigned to drink the fructose-sweetened beverages had developed more adverse lipid profiles," Stanhope said. The conclusion? Americans may pay a high price indeed for their low-priced sweet drinks.


Kimber Stanhope, MS, RD. Stanhope is a registered dietitian with a master's degree in nutrition. For the past 11 years, she has been laboratory manager and research associate in Peter Havel's Research Laboratory in the Department of Nutrition, University of California, Davis.