You're confusing metabolism with hunger. While the two are largely correlated, there is not necessarily a strictly causal relationship. Hunger can occur in the

You're confusing metabolism with hunger. While the two are largely correlated, there is not necessarily a strictly causal relationship. Hunger can occur in the absence of metabolic need due to hormonal signals, environmental cues (such as the smell of food) or psychological cues (social settings, habits). There can be both genetic and environmental factors at hand.