Nat1 KO mice display reduced whole-body energy expenditure. Whole-body oxygen consumption (A), carbon dioxide production (B), energy expenditure (C), respiratory exchange ratio (D), caloric intake (E), drinking (F), and daily activity (G) in WT and KO mice fed RC. Whole-body oxygen consumption (H), carbon dioxide production (I), energy expenditure (J), respiratory exchange ratio (K), caloric intake (L), drinking (M), and daily activity (N) in WT and KO mice fed a HFD. Data are represented as mean ± SEM (n = 10 per group).