Effects of intermittent fasting combined with resistance training on training adaptations: an exploratory multilevel meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and multilevel meta-analysis of randomized trials
PubMed 42421917 · doi:10.3389/fnut.2026.1879031
What was done
Authors conducted an exploratory multilevel meta-analysis of randomized parallel-group or crossover interventions searching PubMed, Web of Science, and SPORTDiscus through March 10, 2026. Eligible trials evaluated intermittent fasting (IF) combined with resistance training (RT) versus RT alone for at least 4 weeks in generally healthy individuals. Adaptations assessed included maximal strength, local muscular endurance, hypertrophy-related outcomes, and explosive/high-speed performance. Risk of bias was evaluated using Cochrane RoB 2, and Hedges' g was calculated using multilevel random-effects models with cluster-robust variance estimation.
What was found
Across 11 studies (303 participants, mostly young adults, interventions lasting 4 weeks to 12 months), IF plus RT yielded training adaptations broadly similar to RT alone overall (Hedges' g = 0.09, 95% CI -0.23 to 0.40). No clear differences were observed across sub-analyses for maximal strength, local muscular endurance, site-specific hypertrophy, explosive/high-speed performance, or body regions; specific numerical values for these individual sub-analyses were not reported in the abstract.
Why it matters
These findings suggest that adhering to intermittent fasting protocols (predominantly time-restricted feeding) does not inherently compromise muscular strength, hypertrophy, or performance adaptations during resistance training.
Limits
The total evidence base remains small (11 trials, 303 total participants) and heavily weighted toward young adults. The abstract does not provide specific numerical effect sizes for individual sub-outcomes, and variability in participant training status, fasting protocols, and nutritional control across studies limits definitive conclusions.
Cited by
- supports Published resistance training studies demonstrate that individuals following daily time-restricted eating are able to maintain and build muscle mass as effectively as non-fasters.