Protein Before or After the Gym? Science Says It (Mostly) Doesn’t Matter
Latest evidence shows protein timing won’t make or break your progress, but one muscle group might see a small lift.
Have you ever rushed to slam a protein shake right after your workout because you didn’t want to “miss the anabolic window”? This new systematic review and meta-analysis cuts through the hype, and for most people, the answer might surprise you.
Aim of the Study
Only randomised controlled trials (rcts) that compare these two timings directly were included to determine whether consuming protein before versus after resistance training leads to different improvements in muscle strength and lean body mass.
Methods
Databases searched: PubMed, Web of Science, Scopus (until January 15, 2024) plus reference lists.
Inclusion: RCTs, ≥4 weeks of training, one group took protein before, the other after training.
Participants: Adults (trained & untrained, younger & older).
Studies included: 6 reports (5 studies), 96–100% diet-matched in most cases.
Protein sources: Mostly whey protein; doses ~25–27g or 0.3 g/kg.
Training: Full-body resistance training, 2–3x/week, over 6–16 weeks.
Outcomes measured: Strength (1RM) and body composition (lean mass, fat mass, muscle thickness).
Results
Upper body strength (chest press 1RM): No meaningful difference between pre- and post-workout protein (SMD: 0.07; p=0.653).
Lower body strength (leg press 1RM): Slight advantage for pre-workout protein (SMD: 0.70; p=0.048), but based on only two small studies (n=53) — so the evidence is weak.
Lean body mass & fat mass: No difference in gains or fat loss between timings.
Muscle thickness (biceps, triceps, vastus lateralis): No difference.
Certainty of evidence: Mostly low to very low. Many studies had a risk of bias and small sample sizes.
Related
Practical Takeaways
For lifters, athletes, and active people:
Don’t stress about slamming protein immediately before or after your session. Total daily protein is more important.
If you enjoy taking protein before training, or it fits your schedule, it might offer a small leg strength benefit, but the evidence is shaky.
Whether your shake is pre- or post-workout, focus on hitting your daily target (e.g., ~1.6–2.2 g/kg/day if building/maintaining muscle).
Choose a protein source you enjoy and tolerate well — whey was most common in studies, but others can work just as well.
The “anabolic window” is wider than you think. Having protein within a couple of hours before or after training seems fine.