Effects of Calorie Restriction With and Without Strength, Endurance or Mixed Training on Fat-Free and Skeletal Muscle Mass in Overweight or Obese Individuals-A Systematic Review With Pairwise Meta-Analysis and Network Meta-Analysis of Randomized Controlled Studies.
Level 1 - systematic review of randomized trials
Systematic review and network meta-analysis of randomized controlled trials
PubMed 42144246 · doi:10.1111/dom.70873
What was done
A systematic review, pairwise meta-analysis, and network meta-analysis of randomized controlled trials from PubMed and Web of Science. The authors compared calorie restriction (CR) alone against CR plus exercise (strength, endurance, or mixed training) on fat-free mass (FFM) and skeletal muscle mass (SMM) in overweight or obese adults across 34 randomized controlled trials with 1,455 participants.
What was found
Pairwise random-effects meta-analysis showed that CR plus exercise preserved significantly more FFM than CR alone (mean difference [MD] = +0.87 kg, 95% CI: +0.59 to +1.16 kg, p <= 0.001), preventing an average of 45.7% of FFM loss. In the network meta-analysis, mixed training showed the largest preservation effect (MD = +1.20 kg, 95% CI: +0.67 to +1.73 kg, p < 0.001, P-score = 0.93), followed by strength training (MD = +0.83 kg, 95% CI: +0.17 to +1.49 kg, p = 0.013, P-score = 0.66), whereas endurance training did not reach statistical significance (MD = +0.51 kg, 95% CI: -0.04 to +1.05 kg, p = 0.067, P-score = 0.41). Only two included studies reported SMM, both showing muscle-preserving effects from exercise.
Why it matters
This review quantifies that adding exercise—especially mixed or strength training—preserves nearly half of the fat-free mass typically lost during caloric restriction.
Limits
Only two studies measured skeletal muscle mass directly rather than total fat-free mass. The abstract does not report intervention duration, magnitude of calorie deficits, dietary protein intake, participant demographics, adherence rates, or functional strength outcomes.
Cited by
- supports When losing weight without resistance training, 25% to 30% of the lost weight comes from muscle mass.