Boston Children's Hospital researchers found that eating such forms of carbohydrates can actually make you hungry for more and stimulates areas of the brain involved in reward and cravings, regions that also play a role in addiction, according to the study published June 26 in the American Journal of Clinical Nutrition. In fact, "Substance abuse and high-glycemic foods may trigger the same brain mechanism tied to addiction," the scientists said in a press release, by activating the dopamine-containing pleasure centers of the brain.
The scientists used "real-time" MRIs to observe the brain activity of 12 overweight or obese men during the crucial four hours after they ate a meal, a period that experts say influences eating behavior during the next meal, according to WebMD. Their blood sugar levels and hunger were also measured.
The "meals" were two milkshakes that had the same calories and taste. The only difference was that one version of the shake contained high-glycemic index carbohydrates, and the other had low-glycemic index carbohydrates.
High-glycemic index carbohydrates are found in highly processed foods such as white bread, white rice and pasta, which are rapidly transformed into sugar in the blood. Low-glycemic index carbohydrates include such items as whole wheat products and sweet potatoes.
After participants consumed the high-glycemic index milkshake, they experienced an initial surge in blood sugar levels, followed by a sharp crash four hours later. This decrease in blood glucose was associated with excessive hunger and intense activation of the nucleus accumbens, a critical brain region involved in addictive behaviors.
The study could have implications for weight control. "Limiting high-glycemic index carbohydrates like white bread and potatoes could help obese individuals reduce cravings and control the urge to overeat," study leader Dr. David Ludwig, director of the obesity prevention center at Boston Children's Hospital, said in the news release.