Why did I eat that? Contributions of individual differences in incentive motivation and nucleus accumbens plasticity to obesity

Obesity is one of the leading causes of preventable illness in the US. The ability to seek out and find food relies in large part on activation on mesocorticolimbic regions including the nucleus accumbens (NAc). There is an emerging literature suggesting that enhanced NAc responsivity to food cues may promote weight gain and hamper weight loss, particularly in obesity-susceptible individuals. This article summarizes recent work examining basal and diet-induced alterations in NAc function and cue-triggered food-seeking in obesity-prone and -resistant rodent models, with an emphasis on differences in glutamatergic plasticity and Pavlovian incentive motivation. Overall, results suggest that enhanced neural and behavioral responsivity to food cues found in humans may be due in part to phenotypic differences between those that are more and less vulnerable to diet-induced weight gain. Furthermore, consumption of sugary, fatty foods results in enhanced NAc function that may help explain the drivers of initial weight gain and the difficulty some people have maintaining long-term weight loss.