Brain chemistry is different in obese people

Brain chemistry in obese people functions slightly differently than in lean people. This impacts eating habits as well as response to food cues, say US researchers in «Molecular Psychiatry».

Scientists at the National Institutes of Health Clinical Centre examined 43 men and women with varying amounts of body fat. During the study period, the participants followed a set schedule for eating, sleeping and activity. Using positron emission tomography (PET) helped evaluate the brain sites in which dopamine was active. In addition, a detailed questionnaire helped determine to which extent the participants tended to overeat.

The study showed that obese people had higher dopamine activity in those regions that are responsible for forming habits and lower activity levels in regions responsible for reward. This could, on the one hand, lead to obese people being more drawn to food triggers and tending to overeat more often, and on the other hand, to considering eating less rewarding and more habitual.

But it still remained unclear whether obesity is the cause or the effect of altered dopamine activity, says study author Kevin D. Hall. Further research was needed to clarify this question and to study whether dopamine activity changes when people change their diet, physical activity behaviour or their weight.