Neurobehavioral Inhibition of Reward‐driven Feeding: Implications for Dieting and Obesity

Abstract

OverviewThe development of effective weight loss interventions requires a thorough understanding of the motivational factors that drive and inhibit the overconsumption of food. Obesity was once believed to result purely from disruptions of homeostatic mechanisms controlling food intake. However, it is increasingly recognized that much of the excess caloric intake in obesity is driven by pleasure or the rewarding properties of readily available palatable food (1,2). It is important to note that the motivation underlying this reward-driven or "hedonic" feeding appears to have a different neurophysiological basis than homeostatic controls over energy balance, though the hedonic and homeostatic systems do interact (3). Recently, a surge of research has linked the appetitive motivation to consume palatable food to activation of the mesolimbic dopaminergic system, a neural pathway also implicated in drug addiction and addictive behaviors such as gambling (4). As a result of these findings, a view of obesity as a "disorder of appetitive motivation" has gained prominence among a growing number of obesity researchers. However, a model of hedonic feeding based purely on appetitive motivation has limitations, including an inability to explain instances of feeding behavior parsimoniously in both dieters and nondieters. The aim of this review is to summarize the strengths and weaknesses of the appetitive model, present the extant literature linking control of hedonic feeding to inhibitory processes localized in the prefrontal cortex (PFC), and delineate a theoretical model in which hedonic feeding is viewed as the product of an interaction between appetitive motivation and inhibitory control. Appetitive motivation in hedonic feedingThe human feeding system leaves room for dessert. Humans will continue to consume palatable food even after energy requirements have been met and homeostatic satiety signals have been engaged. This consumption is clearly not driven by an acute need for calories, and hedonic factors (taste, pleasure, reward) play a large role in this type of feeding. Simply stated, the hedonic feeding model holds that palatable food consumption in the absence of an energy deficit (or the physiological signals associated with energy deficit) is driven by an appetitive motivational state referred to as "hedonic hunger" (2), and not by homeostatic controls over feeding. (For discussion of the role of reward in homeostatic feeding, which may be subjectively associated with escape from hunger rather than the pleasant tastes and textures of palatable food, see ref. (5).) evolutionary pressures for hedonic feedingHedonic feeding has an evolutionary basis. Modern humans preferentially overconsume sweet and high-fat palatable foods (6). Hominids subsisted as hunter-gatherers for the majority of evolutionary history and access to these types of foods (e.g., fruits, animal meat) was presumably limited. Hunting or prolonged foraging would often have been required to obtain sweet and high-fat foods, and it is likely that the ca...

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