Individual differences in the neurophysiology of reward and the obesity epidemic.

The obesity epidemic has unfolded in a matter of decades, not millennia, and therefore cannot be attributed to a drift in the genome. Rather, the temporal characteristics of the epidemic more closely track environmental and lifestyle changes, such as reduced physical activity, increased availability of palatable and energy-dense foods and drinks, and increased acceptance of eating outside of meal time (among others). One important observation is that not everyone is becoming obese. This suggests that individual factors interact with recent environmental changes to predispose some to overeat. One hypothesis that has been gaining traction in the neuroscience community is that individual differences in the neural encoding of foods may predispose some to overeat in the presence of a surplus of energy-dense, palatable foods and drinks. The aim of this review is to highlight several possible ways by which individual differences in the neurophysiology of food reward may lead to overeating.