Do you have to eat protein within 30 minutes of training?

No. The anabolic window — the idea that there is a narrow post-workout period in which protein must be consumed or the session is wasted — has not held up well, and the current picture is far more relaxed.

The original reasoning was that muscle protein synthesis is elevated after training and nutrients delivered immediately would be used most effectively. The elevation is real. What was wrong was the timescale: muscle protein synthesis stays elevated for around 24 to 48 hours after a training session, not 30 minutes. The window is a barn door.

What the research actually shows is that total daily protein intake is by far the dominant variable for muscle growth. Studies comparing immediate versus delayed post-workout protein, with total intake matched, generally find no meaningful difference.

One genuine nuance: if you trained fasted, or your last meal was many hours earlier, eating reasonably soon afterwards makes sense — but that is about your overall daily intake and how long you have gone without amino acids available, not about a magic window. If you ate a protein-containing meal an hour or two before training, those amino acids are still circulating during and after the session anyway.

Practical guidance: hit your daily protein target, spread it across three or four meals through the day, and eat when it suits you. A meal within a couple of hours of training is perfectly sensible; sprinting to a shaker in the changing room is not necessary.

Where timing does matter more is carbohydrate replenishment for endurance athletes training twice in a day, where glycogen must be restored quickly. For most people training once daily, overnight recovery is ample.