All sugars do not satiate our appetite equally, according to a report recently presented at the American College of Neuropsychopharmacology annual meeting. Researchers from the University of Southern California (USC) found that fructose heightens the response of brain reward circuits when exposed to food cues. The result: we want to eat more.
First, here’s a primer on sugar. Glucose is the sugar that your body primarily uses for energy; it’s usually produced when our bodies digest complex carbohydrates such as sweet potatoes and whole grains. Fructose is a simple sugar that is found in fruit, but it’s also the added into products in the form of high-fructose corn syrup. Its ingestion produces smaller increases in the hormones that tell your body is satiated compared to glucose. Previous studies have found that glucose reduces activity in the part of the brain called hypothalamus that has been associated with satiety. In comparison, fructose does not trigger this same activity.
To build on this knowledge, USC researchers had 24 subjects drink a beverage containing either glucose or fructose and then asked the subjects to view pictures of food, such as chocolate cake. While they were viewing the images, the researchers used functional magnetic resonance imaging (aka fMRI) to examine the brain’s responses and asked the subjects how much they wanted to eat. The food cues produced an increased desire to eat and activation in a part of the brain’s reward circuit; specifically in the nucleus accumbens. This effect was greater after consuming the fructose drink. But that isn’t the only enhanced effect that fructose had: it also resulted in greater hunger and motivation to eat compared to the glucose drink.
Bottom line: Read your food labels because high fructose corn syrup hides in the darnest places. And while you’re at it, check your hunger cues after eating fruit. If you find that you’re ravenous after eating a lot of fruit, you may want to cut back on how much you consume. Fructose is fructose and this study suggests that consuming it may promote overeating.