Psychobiological traits in the risk profile for overeating and weight gain.

Our dramatically changed food environment--since periods in our history when food sources were highly constrained--has presented new challenges for obesity research. For example, these alterations have strongly emphasized the physiological differences between the homeostatic and the hedonic regulation of food intake--the latter being largely responsible for the pronounced increase in obesity in the past few decades. There is also increasing agreement that compulsive overeating shares many parallels with addiction disorders such as drug abuse. These factors have also fostered a renewed interest in identifying individual differences in personality and motivational systems that increase the risk for overeating and weight gain in our population. Reward sensitivity has been the focus of a recent body of compelling research, with evidence favoring two seemingly opposite points of view. On the one hand, studies have found support for a link between low reward sensitivity and obesity, whereas other evidence suggests that a strong appetitive motivation leads to overeating and weight gain. Arguments are provided to reconcile these apparently disparate theories. Finally, the role of impulsivity and its links with symptoms of attention deficit/hyperactivity disorder are discussed, as well as their respective roles in the risk profile for obesity.