Over-eat but dont get fat?

ATP-Sensitive Potassium Channel-Deficient Mice Show Hyperphagia but Are Resistant to Obesity.

"Body weight homeostasis is maintained through the balance between energy expenditure and energy intake, and these processes are controlled in the hypothalamus - the center for body weight regulation."

"When anorexigenic peptide is elevated, melanocortin receptor 3/4 in the paraventricular nucleus of the hypothalamus is activated and satiation and thermogenesis are induced. Increased orexigenic peptide activates the Y1/5 receptor in the paraventricular nucleus of the hypothalamus, induces a sense of hunger, and halts thermogenesis"

"This study demonstrated that Kir6.2-deficient mice showed increased hypothalamic NPY expression accompanied with increased caloric intake, decreased visceral fat mass, and resistance to the induction of obesity by a high fat diet compared to the levels in C57BL/6 mice."