You’ve heard it before, and you’ll probably hear it again: You have to eat or gulp down a protein shake within 30 minutes of completing your last rep, or you’ll miss the “anabolic window” and risk losing the muscle you’ve worked so hard to build in the gym. Hell, you may have even learned it from us, because it used to be one of the universal rules of bodybuilding.
Lifters have long believed that during the anabolic window, a quick-release protein like whey powder and some quick-digesting carbs would help refuel muscle tissue that was broken down throughout the session, prevent muscle from breaking down further, and increase muscle-protein synthesis.
But times change, and a study review in the Journal of the International Society of Sports Nutrition questions that rule. Basically, there’s not enough definitive proof that eating within a 30-minute window is more effective than eating within a few hours post-workout. And if you’re training fasted, it can actually boost protein synthesis.
One of the biggest takeaways from the meta-analysis was that most past studies on the anabolic window theory assumed that athletes were working out in a fasted state.
It points out that if you’re working out in the morning, eating some protein and carbs shortly after you train can boost protein synthesis, because your body would be going from a catabolic state (breaking muscle down for energy) to anabolic (building muscle). If you’re not training fasted, though, it may not be as important to get a meal in the second you’re done. A meal one to two hours before your workout can be enough to take you through your training session and then some, according to the analysis.
That’s not to say a balanced pre- and post-workout meal shouldn’t be a priority; it just doesn’t necessarily have to be within 30 minutes of your last rep. Researchers recommend eating within three to four hours pre- and post-workout, and unless you’re intermittent fasting, you’d probably do that anyway.
If it still makes you feel better to chug a shake as you leave the gym, it’s definitely not going to hurt your gains. But rest assured knowing that if you end up eating later, there’s no solid proof that you’ll be losing out on precious muscle.
