Indirect calorimetry measurements

Mice (12 weeks old) were acclimated in metabolic cages (TSE Phenomaster, Chesterfield, MO) for 2 days of adaptation. After 2 days of housing, mice were recorded for 3 minutes every hour for 2 consecutive days with the following measurements: gas exchange [rate of O₂ consumption (VO₂) and rate of CO₂ output (VCO₂)], food intake, and physical activities. Energy expenditure (EE) was calculated according to the manufacturer’s manual. Values were normalized by body weight to the power of 0.75. The respiratory exchange ratio (RER) was estimated by calculation of the ratio of VCO₂/VO₂ (25).