Weight-related changes in MRI-derived measures of body composition and liver steatosis: a large-scale analysis for obesity trial design

This study uses gold-standard, quantitative MRI to establish normative benchmarks for changes in visceral fat, liver fat, muscle volume, and muscle fat infiltration that occur following real-world weight loss or weight gain in ~3,000 adults. These reference data, derived in the pre-incretin era from the UK Biobank, directly enable robust obesity clinical trial design: powering sample size calculations, defining placebo arm behaviour, and supporting label claims for emerging weight-loss therapies.