Mixed
Dietary weight loss stabilizes the proportion of lean mass lost (%LML) at approximately 25-33% once total weight loss exceeds 5%, contradicting the hypothesis that lean loss increases proportionally with greater weight loss.
When you lose weight through diet, you will lose some muscle along with fat. This is normal and accounts for about 25-33% of the total weight lost, regardless of how much weight you lose. Men tend to lose a slightly higher percentage of lean mass than women. To minimize this, combine your diet with resistance training and adequate protein intake, but do not fear that larger weight loss equals disproportionately larger muscle loss.
Contrary to our hypothesis, %LML plateaus with greater weight loss. Moreover, men experience greater %LML than women.
Why this rating
Secondary analysis of a large, randomized controlled trial (DIETFITS) with DXA measurements, though post-hoc stratification introduces some variability.
Source
Body composition changes after 6 and 12 months of dietary weight loss: insights from the DIETFITS trial
Sun H. Kim et al. · Journal of the Endocrine Society · 2026
DOI 10.1210/jendso/bvag015
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