1 · Two eating systems · homeostatic vs hedonic
Two systems drive eating: a homeostatic one for eating when hungry and stopping when full, and a hedonic dopamine pathway for eating for pleasure, even when not hungry.You have two eating systems:1. Homeostatic: arcuate nucleus integrates leptin, ghrelin, insulin — eat when hungry, stop when full. Metabolic need-driven.
2. Hedonic: mesolimbic dopamine pathway (VTA → NAc) — eat for pleasure, even when not hungry. Reward-driven.
In food-scarce evolutionary environments, the two cooperated: hedonic drive encouraged overeating when high-energy food was available. But in the environment, the hedonic system hijacks eating decisions — you eat not because you need energy, but because dopamine is calling.