I couldn’t tell you where I first heard it, but I’ve lived by the rule that I need to eat protein within an hour of finishing a workout if I want to see any gains. So after crushing a workout, I’d rush home to throw together a protein smoothie or scarf down a piece of chicken breast, convinced that all that hard work was going to waste with every passing minute.
That’s the thinking behind the “anabolic window,” a short period after exercise when your muscles are supposedly primed to put protein to work repairing and building muscle. Some have even claimed that taking advantage of this window could lead to dramatic improvements in body composition. But how much does timing really make a difference when it comes to protein after a workout? Or is how much protein you eat throughout the day more important than when you eat it? We asked an expert in exercise physiology and sports nutrition to separate fact from fitness hearsay.
Experts Consulted
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Dr. Kimberly Stein, PhD is senior principal scientist at Gatorade Sport Science Institute (GSSI) with a background in exercise physiology and sports nutrition. At GSSI, she oversees programming in the translation of scientific information for stakeholders across the sport and life science spaces, including athletes, RDs, coaches, and more.
What Is the “Anabolic Window,” and Is It Real?
We know we need protein to help our muscles recover and grow. But according to the theory of the “anabolic window,” there’s a 30- to 60-minute sweet spot after exercise when your muscles are especially receptive to it. The idea is that eating protein during this brief timeframe boosts muscle protein synthesis (AKA the process of repairing and building muscle), helping you get the most out of your workout.
“There was a period of time when we thought that the muscle was most responsive to eating protein for ~45 minutes after a workout, hence the idea of an “anabolic window,” says Dr. Kimberly Stein, PhD, senior principal scientist at the Gatorade Sports Science Institute. But the science since says there’s more to it. “Protein research has evolved and we now understand that the muscle is responsive to dietary protein for much longer, about 24-48 hours depending on the type of workout,” Dr. Stein explains.
A 2024 review found that protein intake can enhance muscle mass, whether it’s consumed immediately after exercise or not. Another review reported that the muscle-building effects of having protein can last up to six hours, rather than ending once that short post-workout “window of opportunity” closes.
The point is no, your muscles don’t lose out after the 45-minute clock runs out. In fact, how much daily protein you eat seems to be the number one factor in helping your workouts translate into muscle growth. “In order to rebuild muscle after a workout, it appears that total daily protein intake, ideally eaten in smaller amounts every 3-4 hours throughout the day, is more important than the exact post-exercise timing,” Dr. Stein confirms.
How Long After a Workout Should You Eat Protein?
While eating protein after you sweat it out helps fuel muscle recovery and growth, you don’t have to sprint to the nearest protein source the second you finish your last rep. The International Society of Sports Nutrition advises eating high-quality protein within two hours of exercise to stimulate muscle protein synthesis. But that doesn’t mean any protein you eat after those two hours are up is pointless. “There’s no longer a specific timing recommendation for protein intake after a workout,” Dr. Stein says. Still, she encourages getting some protein shortly after finishing a workout to make it easier to hit your daily target without having to pack it all into one or two meals.
Research suggests that when you should eat protein after hitting the gym depends on when you last ate, how much protein you’ve consumed, and whether you exercised on an empty stomach. If you had a protein-rich meal an hour or two before your workout, for example, you can probably take your time eating protein post-sweat session (consuming protein before exercising stocks your protein stores so they’re ready to help your muscles grow when the time comes). But if you worked out in the morning without having breakfast first or you haven’t eaten for several hours, getting protein in sooner rather than later might make more of a difference.
The takeaway? Consider the two-hour timeline a general rule of thumb, not a hard deadline. Your last meal, how much protein it contained, and whether you exercised on an empty stomach all factor into when you should eat protein after a workout.
Does Eating Protein Before a Workout Count?
Dr. Stein says it depends on your fitness goals and the type of workout you’re doing. ”For muscle building, the most important part is the strength training itself, and all protein eaten throughout the day ‘counts’ since we now understand that total daily intake is more important than just the protein intake around a workout,” she says. And research backs that up: A 2017 study showed similar improvements in muscle size and strength among participants who consumed protein before versus after resistance training. Translation: That pre-workout protein you eat can contribute to muscle gains, too.
If you’re planning a cardio or HIIT workout, Dr. Stein leans toward prioritizing carbohydrates beforehand for energy, saving protein for after and throughout the rest of the day.
How Much Protein Do You Actually Need After a Workout?
The short answer: There isn’t one magic number that works for everyone. Your protein needs can vary depending on your age, sex, body composition, activity level, and goals (like muscle building, weight loss, or overall health). That said, the International Society of Sports Nutrition points to about 20 to 40 grams of high-quality protein per meal to help maximize muscle protein synthesis.
But their guidance also emphasizes that consistently getting enough protein over the course of the day, preferably every three hours, matters more for building muscle than getting a specific amount right after exercise. A 2013 meta-analysis found that the benefits of protein timing on muscle growth were no longer significant once researchers accounted for total protein intake. “The best approach to determining protein needs is to focus on total daily intake and then divide that up into fairly even portions throughout the day, including post-workout,” Dr. Stein echoes.
But how much protein should you aim for overall? Dr. Stein suggests a daily target of about 0.5 to 0.9 grams per pound of body weight. If you’re looking to build muscle with resistance training, she says to shoot for the upper end of that range. For example, if you weigh 140 pounds, that works out to roughly 70 to 126 grams of protein per day. From there, you can divide up your total protein goal into portions of about 20 to 40 grams at each snack or meal, including after a workout.
You don’t have to track every gram, though. Think about where you can work in a little extra protein: add a side of Greek yogurt to your breakfast, toss in edamame to a grain bowl, or reach for cottage cheese when you’re looking for an afternoon pick-me-up.
READ: How Much Protein Do You Actually Need? Experts Explain
Katherine Chang, Wellness Staff Writer
Katherine Chang is The Everygirl’s Wellness Staff Writer with over five years of experience in the health and wellness space. She navigates the latest wellness topics and trends through expert interviews and studies, and she’s always first in line to try them firsthand.
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