Metabolic & Cardiometabolic
post-workout protein timing has marginal effect on muscle growth
In plain terms: Is the post-workout 'anabolic window' only marginally important?
Yes — the 'anabolic window' is largely a myth: when total daily protein is adequate, timing it tightly around the workout makes little measurable difference to muscle or strength.
Evidence ladder
How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."
Top evidence so far: All trials, pooled (Meta-analysis)
How the studies fall
The evidence (5)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Schoenfeld 2013 · J Int Soc Sports Nutr | meta-analysis | supports | high | Meta-regression found no significant effect of protein timing on strength/hypertrophy once total daily protein was controlled; total intake was the key predictor. |
| Kerksick 2017 · J Int Soc Sports Nutr | mechanism | mixed | moderate | ISSN position stand holds nutrient timing may aid recovery/MPS but that meeting total daily protein is the dominant factor, with modest timing effects. |
| Klemp 2025 · J Int Soc Sports Nutr | RCT | supports | moderate | RCT in older men found neither post-exercise nor pre-sleep protein enhanced muscle thickness/strength over training alone, arguing timing is marginal. |
| Schoenfeld 2017 · PeerJ | RCT | supports | moderate | RCT found immediate pre- vs post-exercise protein produced similar muscle, strength and body-composition changes, refuting a critical narrow window. |
| Aragon 2013 · J Int Soc Sports Nutr | mechanism | supports | moderate | Review concluded the post-exercise anabolic window is much wider than believed and its narrow importance is not supported when daily protein is adequate. |
Disagree, or know a study we missed?
We grade by evidence, not opinions. The way to weigh in is to point us to a study we haven't cited (check the evidence table above first), or to flag a problem with one we have. Every submission is reviewed; if it holds up, the grade updates and shows in Science Changes Its Mind.
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Educational only, not medical advice. Grades and scores reflect published evidence weighted by study design and quality; see the methodology.