WT and KO male littermate mice fed on HFD for 1 week (body weight, WT, 28.64±1.87 g, n=8; KO, 27.98±1.56 g, n=9; P>0.7) were used. To measure metabolic rate, the mice were housed individually in a combined indirect calorimetry system (CaloSys Calorimetry System, TSE Systems, Inc., Bad Homburg, Germany) as previously described4. Each mouse was assessed for 72 h in the fed state to determine the metabolic rate. After an acclimation period of 4 days, heat generation, O2 consumption, and CO2 production were measured and the relationship between metabolic rate and body mass was normalized using metabolic body size (body weight0.75).
