Poor early growth is associated with Type II diabetes, hypertension and other features of the metabolic syndrome in adulthood. It has been suggested that this results from the development of a thrifty phenotype by a malnourished fetus. Such a phenotype would predispose the offspring to the development of obesity if born into conditions of over-nutrition. The present study aimed to determine if early nutrition affected subsequent development of obesity. Mice were established as follows: (a) controls (offspring of control dams), (b) recuperated (offspring of dams fed a low-protein diet during pregnancy, but nursed by control dams) and (c) postnatal low-protein (offspring of control dams nursed by low-protein-fed dams). Mice were weaned on to standard laboratory chow or a cafeteria diet. Recuperated offspring, although smaller at birth (P<0.01), caught up and exceeded the weight of control offspring by 7 days of age (P<0.001). Postnatal low-protein offspring were smaller than controls by 7 days of age (P<0.001). Recuperated animals gained more weight than controls when given free access to a highly palatable diet (P<0.01). Postnatal low-protein animals showed no additional weight gain when given a highly palatable diet compared with chow-fed litter-mates. These results suggest that the early environment has long-term consequences for weight gain. These programmed responses are powerful enough to block excess weight gain from a highly palatable diet and, thus, have major implications for the drug-free regulation of food intake and obesity.