Where the 30-minute rule came from
The anabolic window was born from early studies showing that muscle protein synthesis spikes after training — combined very profitably with supplement marketing. The logic sounded airtight: train, create the demand, then rush protein to the muscle before the window “closes.”
The problem is that those early studies mostly tested people training fasted, and compared a post-workout shake against nothing at all. Of course the shake won. The real question — does timing matter once you're already eating enough protein? — took another decade to answer properly.
What the evidence actually shows
In 2013, Schoenfeld and colleagues meta-analysed 23 studies on protein timing and found a small apparent benefit to post-workout protein — which completely disappeared once total daily protein intake was matched between groups. In other words, the people who timed their protein were simply eating more of it. Timing was a passenger; total intake was driving.
The ISSN's 2017 position stand lands in the same place: total daily protein is by far the dominant factor. Nutrient timing is, at best, a small optimisation on top of an already-adequate intake — not the foundation.
The window is much bigger than 30 minutes
If you ate a protein-containing meal in the few hours before training, your blood amino acids are still elevated when you finish — the “window” is effectively 4–6 hours wide, not 30 minutes. The panic only makes sense if you train completely fasted, in which case getting protein in within an hour or two after is sensible.
So the person sprinting for a shaker bottle mid-gym is optimising something that barely exists, while the person who quietly eats enough protein across the day has already won.
The timing that does matter: distribution
Here's the timing rule with actual evidence behind it: spread your protein across the day. Research supports roughly 0.4g per kilo per meal, across at least four meals spaced 3–4 hours apart, for maximising muscle protein synthesis (Schoenfeld & Aragon, 2018).
Why? Muscle protein synthesis maxes out per meal — around 20–40g for most people — so one giant 100g steak dinner wastes much of its potential while breakfast gets nothing. Four decent hits beats one heroic one.
What about protein before bed?
Pre-sleep protein is the one timing strategy with decent direct evidence: studies on casein before bed show increased overnight muscle protein synthesis, and longer trials suggest it can add a small edge to muscle and strength gains. It's not magic — it's just a well-placed fourth or fifth protein hit.
In practice: a bowl of Greek yogurt, cottage cheese or a casein shake before bed is a low-effort way to cover the 7–9 hour overnight fast. Worth doing; not worth stressing over.
Practical timing for normal life
Stop timing your shake with a stopwatch and fix the structure instead: protein at breakfast, lunch, dinner and one more time (snack or pre-bed). If training falls between meals, eat normally around it. That's the entire timing strategy, and it covers everything the research supports.
Want the per-meal number for your bodyweight? Our protein calculator splits your daily target into four meals automatically.