Study Links Obesity to Brain Patterns

Obese people may gain weight when they eat because their brain takes longer to signal that they are full, according to scientists at the University of Florida and the University of Texas. The researchers used functional magnetic resonance imaging to study how human brains react when people eat.

Dr. Yijun Liu, assistant professor of psychiatry at the University of Florida College of Medicine, noted that in normal-weight subjects the brain reacts to food intake in about 10 minutes, while in obese people, the same reaction takes longer—about 14 minutes. As reported in Nature (June 29, 2000), 18 subjects fasted for 12 hours, then underwent brain scans as they were given a dextrose and water solution.

Dr. Liu and colleagues found that a peak in brain activity, lasting about two minutes, occurred about 10 minutes after people were given the water solution. The peak corresponded directly with increased sugar and insulin levels in the blood. The scientists believe the peaks are a “satiety signal” that tells people when they have had enough to eat. According to Dr, Liu, the results of the study showed a connection between the changes that occur in the human brain after eating and the traditional biochemical indicators in the body, which are increases in the levels of glucose and insulin in the blood.

Dr. Peter Fox, director of the Research Imaging Center at the University of Texas, said the study bolsters the long-standing adage: “Don’t gobble your food.”