Humans and other warm-blooded animals living with continuous access to a va
riety of good-tasting foods tend to eat too much and suffer ill health as a
result-a finding that is incompatible with the widely held view that hunge
r and eating are compensatory processes that function to maintain the body'
s energy resources at a set point. The authors argue that because of the sc
arcity and unpredictability of food in nature, humans and other animals hav
e evolved to eat to their physiological limits when food is readily availab
le, so that excess energy can be stored in the body as a buffer against fut
ure food shortages. The discrepancy between the environment in which the hu
nger and eating system evolved and the food-replete environments in which m
any people now live has led to the current problem of overconsumption exist
ing in many countries. This evolutionary perspective has implications for u
nderstanding the etiology of anorexia nervosa.