Mixed
Diet-based weight loss interventions result in minimal loss of appendicular lean soft tissue (a surrogate for skeletal muscle), with losses accounting for less than 10% of total mass loss after adjusting for fat-free adipose tissue.
If you are losing weight through diet alone (without resistance training), you will not lose significant muscle mass. The study found that lean tissue loss was minimal (less than 10% of total weight lost) and that your muscle mass relative to your new body size actually increased. You do not need to fear muscle loss as a barrier to starting a diet.
Appendicular LST losses comprised <10% of total mass loss after adjusting for FFAT. Appendicular LST relative to body size also increased at 6 mo (P < 0.001).
Why this rating
Large cohort (n=374), randomized controlled trial secondary analysis, rigorous statistical adjustments (FFAT correction, proteomics).
Source
Diet-based weight-loss intervention is not associated with a meaningful change in lean soft tissue
J. Roberts et al. · American Journal of Clinical Nutrition · 2026
DOI 10.1016/j.ajcnut.2026.101251
Related findings · Mixed
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