Lean mass preservation

Lean mass preservation means holding on to muscle and other non-fat tissue while losing weight. Weight lost quickly, by any method, is never purely fat: a share comes from lean tissue, and the faster and more severe the deficit, the larger that share tends to be.

It matters because muscle is what carries strength, function and metabolic health into later life, and losing it is far easier than rebuilding it. This is the reason resistance training and adequate protein are emphasised alongside any substantial weight loss, including weight loss driven by appetite-reducing medication, where intake can fall well below what protein needs require.

In practice, the two well-supported protective levers are resistance training two or more times a week and meeting protein needs across the day; the position-stand evidence on protein and exercise is the reference point.

Sources

• Jäger R, et al. ISSN position stand: protein and exercise. J Int Soc Sports Nutr 2017;14:20