What's So Bad About High Fructose Corn Syrup?

Do studies show that HFCS amps up your appetite?

People often confuse HFCS with plain fructose and, in fact, a number of studies in animals and humans suggest that consuming pure fructose may not satisfy hunger the same way pure glucose does.

Both fructose and glucose trigger reactions in the body that eventually lead to feeling full, says Kathleen Melanson, Ph.D., R.D., a professor of nutrition and food sciences at the University of Rhode Island. But glucose does this more efficiently. When you consume glucose, the pancreas releases insulin, which, in turn, causes an increase in leptin, a hormone that tells the brain we’ve eaten enough. Glucose also blunts the effects of ghrelin, a “hunger hormone” that makes us want to eat more. Pure fructose doesn’t activate these same “fullness” cues, explains Melanson.

But high-fructose corn syrup isn’t pure fructose (100%-fructose foods don’t exist outside of the laboratory; neither do 100%-glucose foods). High-fructose corn syrup is half fructose and half glucose—just like table sugar is. And, because they both contain glucose, HFCS and table sugar do activate leptin and ghrelin systems, says Melanson. In fact, they seem to affect them very similarly.

In a 2007 study of 30 women, Melanson and her colleagues looked at whether drinks sweetened with HFCS affected appetite differently than drinks sweetened with sucrose. They found no differences in the women’s insulin, leptin and ghrelin levels—or in the women’s own ratings of hunger. (Critics have carped that PepsiCo helped support the research, but the findings haven’t been disputed, and other studies show similar results.) “There’s no evidence to date that HFCS affects appetite any differently than sucrose,” agrees Karen Teff, Ph.D., a physiologist at Monell Chemical Senses Center in Philadelphia who has also studied this issue extensively.