Role of the arcuate nucleus of the hypothalamus in regulation of body weight during energy deficit

Acute or long-term energy deficit in lean or obese rodents or humans stimulates food intake or appetite and reduces metabolic rate or energy expenditure. These changes contribute to weight regain in post-obese animals and humans. Some studies show that the reduction in metabolic rate with energy deficit in overweight people is transient. Energy restriction has been shown in some but not all studies to reduce physical activity, and this may represent an additional energy-conserving adaptation. Energy restriction up-regulates expression of the orexigenic neuropeptide Y, agouti related peptide and opioids and down-regulates that of the anorexigenic alpha-melanocyte stimulating hormone or its precursor pro-opioomelanocortin and the co-expressed cocaine and amphetamine-regulated transcript in the arcuate nucleus of the hypothalamus. Recapitulating these hypothalamic changes in sated animals mimics the effects of energy deficit, namely increased food intake, reduced physical activity and reduced metabolic rate, suggesting that these energy-conserving adaptations are at least partially mediated by the hypothalamus.