Using different mouse models, Koch et al. demonstrated: first, that 6-weeks treatment of obese wild type mice with a leptin neutralizing antibody drives a 10% reduction in food intake; second, that hyperleptinaemia is a driving force of metabolic disorders; third, that a partial restoration of leptin levels in plasma leads to improved leptin sensibility and insulin sensitivity, and reduces weight gain and hepatic steatosis [48]. The gene discussed is LEP; the disease is Hepatic steatosis.