Previous calorie reduction significantly enhances orexigenic hormone responses to high-fat diet. A, MCH levels in the LH were significantly increased in calorically restricted mice refed on a high-fat diet compared with ad libitum mice refed on high fat (n = 4–5) (*p < 0.05). B, Orexin levels in the LH were significantly increased in restricted mice refed on a high-fat diet compared with restricted mice refed on chow or ad libitum mice refed on high fat (n = 4–5) (*p < 0.05). Data are mean ± SEM.