Is there an anabolic window after training?

What the research actually shows

The anabolic window is the most durable piece of gym folklore there is, and it has a plausible mechanism behind it: training sensitises muscle to amino acids, so feeding it soon afterwards should help. The problem is that when you line up every training study that actually measured muscle growth, the effect stops behaving.

The pooled analysis (timing groups versus non-timing groups, nothing controlled) showed a small-to-moderate benefit for muscle size and nothing for strength. Then they built the full meta-regression model, and:

• The timing effect vanished. With covariates in the model, there was no significant difference between timed and untimed protein for either strength or hypertrophy.
• Total daily protein was the strongest predictor of growth. The studies that "proved" timing had mostly given the timing group a protein supplement and the control group nothing. They weren't comparing timing. They were comparing more protein to less protein.
• Strength showed nothing even before controlling. Which is what you'd expect if the effect were a confound rather than a mechanism.

This is worth sitting with, because it's the single most common way nutrition research gets misread: the intervention group did two things at once, and the headline credits the wrong one.

Where timing still earns its keep

Discarding the 30-minute rule doesn't mean timing is irrelevant. It means the relevant unit is the day, with two practical exceptions:

• If you train genuinely fasted (nothing since dinner, morning session), you've been catabolic for 10+ hours and there's a reasonable case for eating soon after. Not because of a window, but because you have a lot of protein left to fit into the day.
• If you train twice a day or have a competition later, recovery nutrition is about refuelling for the next session, which is a different question entirely.

Otherwise, a protein-containing meal within a few hours either side of training covers it. The pre-workout meal is still digesting during and after training: amino acids from a meal eaten two hours before you lift are still entering the bloodstream while you're in the shower.

What the window was distracting you from

Every hour spent worrying about a shake is an hour not spent on the number that actually predicted growth in this analysis: total daily protein. Distribution matters a little (four or more feedings of a decent size, which is the practical upshot of the 30 g question), but the total comes first and everything else is a rounding error on top of it.