A study published in Agricultural Research magazine shows that it may be possible to retrain the brain to stop activating its reward centers on exposure to a steady stream of high-calorie foods and visual triggers.
The U.S. Dept. of Agriculture (USDA)-funded study addresses concerns among weight-loss experts that when people get accustomed to eating instant-gratification foods, such habits may be nearly impossible to stop or reverse.
The study volunteers were 13 overweight or obese men and women assigned to one of two study groups. One group was placed on an at-home weight-loss intervention of lower calorie foods for six months with a goal of losing about 1–2 lbs per week. The other was a no-intervention control group eating normally at home. To satisfy brain areas linked with cravings, the intervention group's diet provided about 45–50% of daily calories from "slow-digesting" carbohydrates and high-fiber foods. High-protein foods and healthy fats each provided about 25% of the other daily calories. The group received 1-hr support sessions most weeks and meal plans that centered on hunger reduction, portion-control, and high satisfaction. They were told to evenly space meals and snacks, and to freely use foods from a list of those with very few calories that could be eaten any time. These tips were designed to keep blood sugar levels level (versus spiking) and control hunger.
The team used magnetic resonance imaging (MRI) to assess neuronal activity in the brain's reward-response areas. All volunteers had two MRI brain scans—one at the beginning and one at the end of the six-month study. During scanning, the volunteers were shown 20 images of high-calorie foods and 20 images of low-calorie foods. They rated the desirability of each image on a scale of 1 (none) to 4 (extremely) while blood flow to key brain areas was measured. Higher blood flow indicated greater neuronal activity.
The researchers found that the intervention group achieved significant weight loss—about 14 lbs each. This intervention group had greater neuronal activity on their brain scans when viewing low-calorie food images at the end of the six-month period versus when they viewed the same images before the intervention. The researchers note that more studies are needed to assess whether these positive changes in neuroplasticity can help people sustain weight loss over time.