2.2. Metabolic phenotyping of mice

Indirect calorimetry measurements on mice were performed using the Promethion metabolic cage system (Sable Systems International, Las Vegas, NV, USA). Mice were acclimatised for 72 h in the Promethion system before data acquisition began. The Promethion multiplexed system has a ‘home-like’ environment with each cage containing standard bedding, a food hopper, a water bottle, and an enrichment tube for body mass measurements, all connected to load cells for real-time weight monitoring. Food spillage was collected at the end of the run from each cage, and food intake was corrected accordingly. Instrument control and data acquisition were performed according to the manufacturer's instructions. Raw data were processed using ExpeData software (Sable Systems).

Whole body lean mass, fat mass, bone mineral content (BMC), and bone mineral density (BMD) were measured in mice anesthetised with isoflurane using a dedicated mouse dual X-ray absorptiometry (DXA) (Lunar Piximus II, GE Medical Systems, Madison WI) at 14 weeks of age.