Recent upsurge in research has uncovered distinct circuitries that regulate appetite, energy expenditure and fat accrual under the supervision of hormonal feedback signalling of adipocyte leptin and gastric ghrelin in the hypothalamic integration of energy homeostasis. A host of messenger molecules of diverse chemical composition and origin mediate the crosstalk between the three circuitries. Leptin is now recognized as the mandatory afferent signal in maintenance of weight homeostasis. Leptin insufficiency in the hypothalamus due to diminished transport of leptin across the blood-brain barrier (BBB) imposed by environmental causes, such as consumption of energy-enriched diets and diminished energy expenditure, orchestrates unregulated fat accrual and the attendant disease cluster of metabolic syndrome. Bioavailability of leptin selectively in the hypothalamic targets with the aid of gene therapy successfully averted the environmentally induced metabolic afflictions and normalized lifespan. Thus, sustenance of optimal sufficiency in leptin signalling solely in the hypothalamus is a novel strategy to combat the worldwide epidemic of obesity and metabolic syndrome.