Macro partitioning
In healthy aging men, fat-free mass (primarily skeletal muscle) begins a non-linear decline around age 47, while fat mass increases until approximately age 70-80, resulting in a stable total body weight that masks significant body composition deterioration.
If you are a man over 40, do not rely on body weight or BMI to track your health. Your weight may stay the same while you lose muscle and gain fat. To maintain health, prioritize resistance training to preserve fat-free mass, as aerobic exercise alone was found to be insufficient to prevent this loss in this study.
Fat-free mass increased slightly from age 20 to 47 years and then declined at a non-linear rate with ageing... Fat mass... increased from age 20 years and levelled off at approximately 80 years.
Why this rating
Large longitudinal cohort (n=7265, 38,328 observations) with rigorous statistical modeling (LMM), though restricted to healthy, predominantly white, educated men.
Source
Longitudinal changes in body composition associated with healthy ageing: men, aged 20–96 years
Andrew S. Jackson et al. · British Journal Of Nutrition · 2011
This is one finding among thousands. Every one is graded and traced to its source, so you can see what the evidence actually supports. Browse the research →