Anabolic window (or metabolic window)
A theoretical period of 30-60 minutes after exercise when the body is said to be especially receptive to absorbing nutrients for muscle recovery, a belief popularised in fitness.
The “anabolic window” is the idea that after training there is a time window in which eating protein and carbohydrate maximises muscle protein synthesis and glycogen resynthesis.
Scientific status (2024): PARTLY TRUE but greatly exaggerated.
The facts:
- There is indeed an increase in muscle sensitivity after exercise
- Eating carbohydrate and protein soon after exercise speeds up glycogen resynthesis (about 30-50% faster)
- But this speed-up lasts only a few hours and makes no difference if your total intake for the day is adequate
A fresh angle: recent studies (2020-2024) show that if you ate an hour BEFORE training, the anabolic window matters far less. Your total daily intake of protein and carbohydrate matters MUCH more than timing.
Fitness marketing has created an urgency that does not exist: “you MUST have a protein shake within 30 minutes or you lose your gains”. False. If you eat well overall, fine-tuning the timing makes no difference.
One case where timing really does matter: endurance athletes (marathon runners, cyclists) doing efforts of >90 min. There, resynthesising glycogen immediately counts.