Body-fat percentage and muscle mass

BMI can't tell muscle from fat: the “normal BMI, high body fat” (skinny-fat) phenotype is a hidden form of metabolic risk, and 20–30% of people over 60 fit it. The goal isn't minimal fat but enough muscle: low muscle mass independently predicts mortality after 50.

DEXA every 1–2 years from 40; smart scales only for trends.

Strength training 2–3× a week (the only thing that builds muscle), protein 1.6 g/kg, a mild calorie deficit if fat must go — never aggressive, since muscle goes with it; strength training is mandatory alongside GLP-1 drugs.