Furthermore, studies have shown that excessive energy intake and body fat deposition caused by HFD (high fat diet) lead to resistance to leptin and insulin, whereas loss of Socs3 expression in the brain improves diet-induced obesity, leptin resistance and even insulin resistance.This suggests that the Stat3-Socs3 system in the brain plays a major role in regulating body fat mass. The gene discussed is SOCS3; the disease is obesity due to melanocortin 4 receptor deficiency.