Research Examines Effect of Glycemic Index on Brain
A recent study examining the effects of low- and high-carbohydrate foods on brain activity has purportedly concluded that meals with a high glycemic index (GI) “decreased plasma glucose, increased hunger, and selectively stimulated brain regions associated with reward and craving in the last postprandial period, which is a time with special significance to eating behavior at the next meal.” Belinda Lennerz, et al., “Effects of dietary glycemic index on brain regions related to reward and craving in men,” American Journal of Clinical Nutrition, June 2013. Led by New Balance Foundation Obesity Prevention Center Director David Ludwig, researchers used functional magnetic resonance imaging to analyze the brain activity of 12 overweight or obese men during the four-hour period following consumption of either a low-GI or high-GI milkshake.
The results evidently showed that “cerebral blood flow was greater [four hours] after the high- than low-GI meal in the right nucleus accumbens,” a region of the brain implicated in food intake, reward and craving as well as patterns of substance abuse and dependence. The study’s authors note, however, that determining whether this outcome supports a theory of food addiction would require additional research. “These neurophysiologic findings, together with longer feeding studies of weight-loss maintenance [], suggest that a reduced consumption of high-GI carbohydrates (specifically, highly processed grain products, potatoes, and concentrated sugar) may ameliorate overeating and facilitate maintenance of a healthy weight in overweight and obese individuals,” they ultimately conclude.
“This research suggests that based on their effects on brain metabolism, all calories are not alike,” Ludwig further explained in a June 17, 2013, New York Times blog post. “Not everybody who eats processed carbohydrates develops uncontrollable food cravings. But for the person who has been struggling with weight in our modern food environment and unable to control their cravings, limiting refined carbohydrate may be a first logical step.” See Science Daily, June 26, 2013.
