Protein supplements added squat strength, with conditions
In short
Across 23 trials in 611 healthy young adults, protein plus lifting added 2.63 kg to bench and 7.40 kg to squat versus lifting alone. Squat benefits appeared mainly at ≤12 weeks or with intake around training plus before sleep; timing remains uncertain.
Bench 1RM rose an extra 2.63 kg and squat 1RM an extra 7.40 kg when protein supplementation accompanied lifting. Those are differences against resistance training alone, not total gains. The meta-analysis indexed in PubMed pooled 23 randomized trials with 611 healthy young adults.
How precise were the extra gains?
| Lift | Weighted mean difference | 95% confidence interval |
|---|---|---|
| Bench press | +2.63 kg | 0.77–4.49 kg |
| Squat | +7.40 kg | 2.15–12.66 kg |
Both pooled comparisons had p=0.006. Removing individual studies or study categories preserved the direction and statistical significance. These group averages cannot predict what your next strength test will show.
Do you need a bedtime serving or a 12-week cutoff?
The squat advantage appeared mainly in studies lasting ≤12 weeks, or using protein before and/or after training plus before sleep. This does not mean both conditions had to occur together. Duration moderated squat results in meta-regression (p=0.037); timing was borderline (p=0.073). Subgroup patterns do not isolate a bedtime benefit or prove gains stop after week 12.
What should go in your training log?
- Date the start of supplementation and track training duration.
- Keep habitual protein intake, including food, alongside supplement timing.
- Compare bench and squat 1RM under consistent testing conditions.
In fairlift, read Muscle Index changes against actual Big 3 records and bodyweight changes. Do not add the pooled bonus to your lifts or assume a deadlift benefit. The whey dose and lean mass article addresses a different outcome: this abstract supplies no gram dose to prescribe.
The evidence concerns healthy young adults. Training experience and starting protein intake may affect the extra benefit, so the pooled result is not a universal supplement plan.
Frequently asked questions
How much extra 1RM did supplementation add?
Across 23 randomized trials, supplementation added 2.63 kg to bench and 7.40 kg to squat versus training alone. Those averages are not guaranteed individual gains.
Is protein before sleep essential?
Squat benefits appeared mainly in a subgroup combining intake around exercise with intake before sleep. Timing was only a borderline moderator (p=0.073), so this does not establish bedtime protein as essential.
Does the benefit disappear after 12 weeks?
Benefits appeared mainly in studies lasting ≤12 weeks, but that does not prove an effect vanishes afterward. Study duration was a significant moderator of squat results.
How many grams should I supplement daily?
The abstract does not report a protein dose in grams. It cannot establish a daily supplement dose or a preferred product.
Source: PubMed (published )