Intermittent fasting & muscle
// What the research shows
The meta-analysisMeta-analysis A study of studies: the results of many individual studies are pooled statistically. More in the glossary → by Ho et al. (2024; 7 studies, 164 participants) found that time-restricted eating plus resistance training reduced body weight, fat mass, insulin and cholesterol without affecting muscle mass or strength. A larger analysis of 15 trials (Hays et al., 2025) reached a similar result with exercise in general: slightly less fat, no significant effect on fat-free massLean mass / fat-free mass Everything in the body except fat: muscle, bone, organs and water. More in the glossary →.
// In practice
- If an eating window helps you eat less: go for it, it won't cost you muscle.
- Still get enough protein in the window, ideally spread over 2–3 meals.
- A “fat-burning bonus” beyond calories isn't supported.
// Limitations & open questions
Small studies, short durations, many participants with overweight. The fat loss probably comes mostly from eating less overall.
// Sources
- Meta-Analyse 2024Ho et al. – Time-restricted feeding and resistance training on body composition and metabolic health (Nutrients) ↗
- Meta-Analyse 2025Hays et al. – Effects of time-restricted eating with exercise on body composition in adults (Int J Obesity) ↗
// More from Nutrition
Daily protein
Around 1.6 g of protein per kg body weight is enough for most people. Up to about 2.2 g/kg may still add a little.
Protein per meal
The old rule that “anything over 20–30 g per meal is wasted” doesn't hold up.
Building muscle in a calorie deficit
A deficit slows muscle gain but barely affects strength gains. At around 500 kcal per day, average lean mass gain drops to zero.