The reason behind UCP-1 ablation resulting in obesity is that under thermoneutrality conditions, increased metabolism is not required to maintain the temperature, but under subthermoneutrality conditions, thermal stress is present, and the body utilizes either brown fat in the presence of UCP-1 or other mechanisms such as shivering thermogenesis in the absence of UCP-1, so the exact role of UCP-1 in BAT may be masked by other complementary mechanisms [23]. The gene discussed is UCP1; the disease is obesity due to melanocortin 4 receptor deficiency.