University of California, San Francisco researchers have found that the neurotransmitter serotonin controls feeding rate (how much to eat) and fat storage (what is done with calories in the body) independently.

The research results, based on studies of the worm C. elegans, suggest that weight-loss drugs that increase serotonin levels could work by either suppressing the appetite or increasing metabolism.

The results may explain why two individuals with similar eating and physical activity habits may have very different body weights–because their bodies process the food differently.

Also see Eating and weight gain not necessarily linked, study shows