LEP and nutritional deficiency disease: However, the fact that central and peripheral leptin signalling seem to be blunted in animal models exposed by maternal malnutrition during pregnancy and improved by leptin supplementation during the lactation period, suggests that leptin may exert an essential role, not only in the proper development of hypothalamic circuits involved in the control of energy balance, but also in metabolic programming of adipose tissue and its capacity to respond to leptin and to adapt to different environmental conditions (Fig. 4).