FitProven
Evidence Breakdown
Based on 3 studies
Evidence map
For & against, at a glance
RCT
Pro
Cribb PJ & Hayes A · 2006Medicine and Science in Sports and ExerciseRCT in recreational bodybuilders found that consuming protein/creatine/carbs immediately before and after training resulted in greater gains in lean body mass and strength compared to consuming the same supplement in the morning and evening. However, this study had a small sample size.
0.24
RCT in recreational bodybuilders found that consuming protein/creatine/carbs immediately before and after training resulted in greater gains in lean body mass and strength compared to consuming the same supplement in the morning and evening. However, this study had a small sample size.
Design RCT (0.8) × quality 0.30 = impact 0.24
View sourceMeta-Analysis
Con
Schoenfeld BJ et al. · 2013Journal of the International Society of Sports NutritionMeta-analysis of 23 studies found that total daily protein intake was the strongest predictor of hypertrophy, not the timing of protein intake relative to exercise. The purported narrow "anabolic window" was not supported by the evidence.
0.75
Meta-analysis of 23 studies found that total daily protein intake was the strongest predictor of hypertrophy, not the timing of protein intake relative to exercise. The purported narrow "anabolic window" was not supported by the evidence.
Design Meta-Analysis (1.0) × quality 0.75 = impact 0.75
View sourceNarrative Review
Con
Aragon AA & Schoenfeld BJ · 2013Journal of the International Society of Sports NutritionComprehensive review concluded that the anabolic window is much wider than originally believed. The claim that protein must be consumed within 30 minutes post-exercise for optimal results is not well-supported. A window of several hours appears sufficient.
0.18
Comprehensive review concluded that the anabolic window is much wider than originally believed. The claim that protein must be consumed within 30 minutes post-exercise for optimal results is not well-supported. A window of several hours appears sufficient.
Design Narrative Review (0.3) × quality 0.60 = impact 0.18
View sourceRCT
Pro
Cribb PJ & Hayes A · 2006Medicine and Science in Sports and ExerciseRCT in recreational bodybuilders found that consuming protein/creatine/carbs immediately before and after training resulted in greater gains in lean body mass and strength compared to consuming the same supplement in the morning and evening. However, this study had a small sample size.
0.24
RCT in recreational bodybuilders found that consuming protein/creatine/carbs immediately before and after training resulted in greater gains in lean body mass and strength compared to consuming the same supplement in the morning and evening. However, this study had a small sample size.
Design RCT (0.8) × quality 0.30 = impact 0.24
View sourceMeta-Analysis
Con
Schoenfeld BJ et al. · 2013Journal of the International Society of Sports NutritionMeta-analysis of 23 studies found that total daily protein intake was the strongest predictor of hypertrophy, not the timing of protein intake relative to exercise. The purported narrow "anabolic window" was not supported by the evidence.
0.75
Meta-analysis of 23 studies found that total daily protein intake was the strongest predictor of hypertrophy, not the timing of protein intake relative to exercise. The purported narrow "anabolic window" was not supported by the evidence.
Design Meta-Analysis (1.0) × quality 0.75 = impact 0.75
View sourceNarrative Review
Con
Aragon AA & Schoenfeld BJ · 2013Journal of the International Society of Sports NutritionComprehensive review concluded that the anabolic window is much wider than originally believed. The claim that protein must be consumed within 30 minutes post-exercise for optimal results is not well-supported. A window of several hours appears sufficient.
0.18
Comprehensive review concluded that the anabolic window is much wider than originally believed. The claim that protein must be consumed within 30 minutes post-exercise for optimal results is not well-supported. A window of several hours appears sufficient.
Design Narrative Review (0.3) × quality 0.60 = impact 0.18
View sourceTap any node to expand its detail.
Evidence
PRO (1)
PRO RCTn=17CONFLICTED0.30 Cribb PJ, Hayes A (2006)
Pre/post-workout supplement timing produced greater gains in lean body mass, 1RM strength in 2 of 3 lifts, type II fibre CSA, contractile protein and muscle creatine/glycogen than the same supplement taken morning/evening (all P < 0.05)
RCT in recreational bodybuilders found that consuming protein/creatine/carbs immediately before and after training resulted in greater gains in lean body mass and strength compared to consuming the same supplement in the morning and evening. However, this study had a small sample size.
Weighted 0.30 — 17 analysed of 23 who started (8 vs 9 per group) — very small, with 26% dropout. The supplement was supplied by AST Sport Science and the lead author was a consultant to that company, and the result is positive in the sponsor's favour, which is the combination that most warrants caution. The supplement also bundled protein, creatine and carbohydrate, so the trial cannot attribute the effect to timing as opposed to any single ingredient.
Funding: AST Sport Science supplied the supplement; the lead investigator is a consultant to AST Sports Science — the funder profits from this result.
Medicine and Science in Sports and Exercise
AGAINST (2)
AGAINST Meta-Analysisn=525AGAINST FUNDER0.75 Schoenfeld BJ, Aragon AA et al. (2013)
Total daily protein intake, not peri-workout timing, was the strongest predictor of hypertrophy; the apparent 'anabolic window' benefit disappeared once total protein was controlled for
Meta-analysis of 23 studies found that total daily protein intake was the strongest predictor of hypertrophy, not the timing of protein intake relative to exercise. The purported narrow "anabolic window" was not supported by the evidence.
Weighted 0.75 — k=23 studies; 525 participants pooled for the hypertrophy analysis (478 for strength). Mean PEDro 8.7, so the included trials are of high methodological quality. Industry-funded by a protein-supplement manufacturer -- but the result is a null for the timing effect that the industry markets, and an industry-funded null that cuts against the funder's commercial interest is the strongest form of that evidence, so this is not discounted for bias. Held below the top band because total protein intake was confounded with timing across the source trials, a limitation the authors themselves flag.
Funding: Dymatize Nutrition — this result runs against the funder's own interest, which strengthens it.
Journal of the International Society of Sports Nutrition
AGAINST Narrative Review0.60 Aragon AA, Schoenfeld BJ (2013)
The post-exercise anabolic window is several hours wide, not 30 minutes; the requirement to consume protein within 30 min of training is not well supported
Comprehensive review concluded that the anabolic window is much wider than originally believed. The claim that protein must be consumed within 30 minutes post-exercise for optimal results is not well-supported. A window of several hours appears sufficient.
Weighted 0.60 — No pooled sample size — the paper is a narrative synthesis of the timing literature with no meta-analysis and no formal risk-of-bias appraisal, so sample_size is omitted. Influential, independent (no competing interests declared) and directly on point, but its conclusions rest on the authors' reading of heterogeneous small trials rather than on quantitative pooling, which is why it earns only a middling multiplier within the systematic-review class. No funding statement appears in the paper, so that field is omitted too.
Journal of the International Society of Sports Nutrition