Study suggests link between fructose and obesity
Fructose may be best known to consumers in the form of high-fructose corn syrup, which has long been added to manufactured foods from sodas to cookies.
Distinct from sugar known as glucose (produced by the natural breakdown of complex carbohydrates), fructose is also a "simple" sugar and a natural component of fruit.
However, "in a series of studies we have found that when compared to glucose, the simple sugar, fructose, is a weaker suppressor of brain areas that help control appetite and the motivation to eat," said study co-author Dr. Kathleen Page, an assistant professor of clinical medicine at the Keck School of Medicine of the University of Southern California in Los Angeles.
In other words, people are more likely to remain feeling hungry after a meal with lots of fructose versus one with lots of glucose.
Prior research has indicated that, when compared with glucose consumption, ingesting fructose sparks a smaller release of hormones such as insulin that give rise to a sense of being full, according to background information with the study. Recent investigations have also suggested that only glucose, not fructose, curtails hunger by slowing down activity in a specific region of the brain (the hypothalamus), the researchers said.
The small, new study builds on both findings.
More than two-thirds of American adults are overweight or obese, which puts them at risk of heart disease, type 2 diabetes and certain cancers. Many experts believe that changes in U.S. food production, including widespread use of high-fructose corn syrup, are to blame.
For the current effort, the researchers enlisted 24 men and women ages 16 to 25 to participate in a hunger exercise.
All participants were instructed to consume a drink sweetened with either glucose or fructose. Then they were asked to view images of various foods (including, for example, chocolate cake) and indicate the degree to which they felt hunger. The exercise took place while each was hooked up to a functional magnetic resonance imaging (fMRI) scanner in order to track real-time brain activity in a "reward" center of the brain known as the nucleus accumbens.