Overeating and the Brain: What Causes the Control Problem?
How our brain responds to eating certain foods may hold the key to treating obesity. A study by Dr. Stice (et al) published in Science, 2008, October 17, 322:449, addressed the relationship between obesity and a blunted dorsal striatal response to eating. The amount of a dopamine release from the dorsal striatum is correlated with pleasure from eating. In this study obese individuals were found to have fewer dopamine D2 receptors than lean individuals. Obesity and the reduced number of dopamine D2 receptors has been linked with A1 allele. The obese individuals in the study were thought to be overeating as a compensatory mechanism for the reduced pleasure response.
The study included only females and couldn't distinguish whether overeating high-fat/high calorie food causes, or results, from a hypofunctioning dopamine reward system. It does identify the role of the TaqIA A1allele and suggest that a mechanism exists to cause overeating. This study offers an opportunity to relieve the guilt and shame experienced by many individuals with overeating problems. Further pharmacological and behavioral treatment may now be better able to target the problem.