Feed-forward mechanisms: Addiction-like behavioral and molecular adaptations in overeating

Food reward, not hunger, is the main driving force behind eating in the modern obesogenic environment. Palatable foods, generally calorie-dense and rich in sugar/fat, are thus readily overconsumed despite the resulting health consequences. Important advances have been made to explain mechanisms underlying excessive consumption as an immediate response to presentation of rewarding tastants. However, our understanding of long-term neural adaptations to food reward that oftentimes persist during even a prolonged absence of palatable food and contribute to the reinstatement of compulsive overeating of high-fat high-sugar diets, is much more limited. Here we discuss the evidence from animal and human studies for neural and molecular adaptations in both homeostatic and non-homeostatic appetite regulation that may underlie the formation of a “feed-forward” system, sensitive to palatable food and propelling the individual from a basic preference for palatable diets to food craving and compulsive, addiction-like eating behavior.

Figure optionsDownload as PowerPoint slideHighlights
► Palatable food promotes overeating and weight gain in humans and experimental animals.
► We review evidence for palatability-induced chronic adaptations in reward processing.
► We show that these changes act in a feed-forward manner to promote further overeating.
► They contribute to addictive-like eating behavior during withdrawal from palatability.
► This explains why overeating and obesity are oftentimes lifelong adverse conditions.