(A–D) Oxygen consumption (A, left panel), average oxygen consumption (A, right panel), heat generation (B), spontaneous activity (C), and respiratory exchange ratio (D, left panel), average respiratory exchange ratio (D, right panel), measured in weight-matched mice of 12–16 weeks old (n = 4–5). Measurements were made over a three day period. Gray shades in A and B indicate dark cycles, (E–F) Mice (12–14 weeks old) fed a regular diet (E) or a HFD (F) were deprived of food, exposed to cold (4°C) and core body temperature was measured every hour for three hours (n = 5–9 for regular diet, n = 5–11 for HFD), (G) Core body temperature of mice (12–14 weeks old) fed a regular or a HFD (n = 5–9 for regular diet, n = 5–11 for HFD). *p<0.05, **p<0.01, ***p<0.001. In all panels, data represent mean ± SEM.