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Conventional wisdom — or at least "gym rat" wisdom — says you need to eat protein within an hour of your last rep to maximize the workout's muscle-building effects.
2019-10-27
But the reality is more nuanced, Brad Schoenfeld, an associate professor in exercise science at CUNY Lehman College, said Sunday during a presentation at the Academy of Nutrition and Dietetics' annual Food and Nutrition Conference and Expo in Philadelphia.
While it's true that eating protein after a workout helps repair, and therefore grow, muscle tissues, Schoenfeld's found it's also true that eating protein before gym helps repair and grow muscle tissues. It doesn't matter so much whether or how quickly you eat protein before or after a workout, so long as you're doing it at all.
"If you actually take in pre-workout meals, everything is off the table," said Schoenfeld, who's also the author of "The Science and Development of Muscle Hypertrophy" and owns lookgreatnaked.com.
In the study supporting this conclusion, Schoenfeld and a colleague recruited 21 fit college men and assigned half to take a supplement with 25 grams of protein and 1 gram of carbohydrate before working out and the other half to take the same supplement after working out. Their workouts were the same full-body weight-training routines performed three days a week for 10 weeks.
After measuring the men's muscle thickness, strength, and overall body composition using top-tier techniques like ultrasound and dual X-ray absorptiometry imaging, the researchers found no significant difference in the gains of the men who protein-packed before a workout versus those who did so after hitting the gym.
The findings, Schoenfeld said, suggest the best time to eat protein isn't a narrow one-hour post-workout window, but more like a "barn door" that may open as wide as four to six hours surrounding the workout itself.
"If you're eating breakfast, lunch, and dinner and having snacks in between, you're going to hit your window," he said. "You don't have to sweat."
Studies evaluating how much protein can get used in the body for muscle-building purposes don't tend to look at real, slower-digesting meals.
Meat and Potatoes
How much protein your body can handle at once is nuanced
During his presentation, Schoenfeld also challenged other notions he dubbed "bro science," such as the idea that your muscles can't use any more than 20 to 30 grams of protein at once, so consuming any more than that for muscle-building purposes is worthless.
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While there is some support to that theory, Schoenfeld said, again, it's nuanced. For one, much of the research that's come to that conclusion is based on studies where participants are eating "fast-acting protein" like pure whey supplements alone.
In real life, people tend to eat slower-acting proteins (like meat or eggs) in combination with other macronutrients, like carbohydrates, which slows down the absorption. Those more complex forms slow absorption and theoretically allow some people's muscles to use more than a 30-gram-per-meal cap.
Plus, everyone is different, so such a "cap" may be appropriate for some, but isn't a universal rule.
Rather, "a relatively simple and elegant solution" is to consume 0.4 grams of protein per kilogram of body weight across at least four meals a day if your goal is muscle building, Schoenfeld and a colleague concluded in a paper published in the Journal of the International Society of Sports Nutrition.
That translates to about 27 grams per meal for a 150-pound person, but a whole 45 grams per meal for a 250-pound person.
Still, the researchers conclude, "further research is nevertheless needed to quantify a specific upper threshold for per-meal protein intake."
Anna Medaris is a health correspondent at Insider with more than a dozen years of experience covering women's health, fitness and nutrition, sex and relationships, medical conditions, and psychology. At Insider, she mostly focuses on reproductive health, mental health, and medical misdiagnoses. She also writes wide-ranging features, narratives, and analyses on sensitive topics including addiction, maternal suicide, and accidental deaths. Anna loves dissecting quirky, cultural trends too, like cold-water swimming, White Claw, and water-cooler chatter. Prior to joining Insider in 2019, Anna was a senior health editor at U.S. News & World Report and, before that, an associate editor at APA's Monitor on Psychology magazine.She has also written for the Washington Post, the Washington Post Magazine, Women's Health, and Cosmopolitan. She regularly appears as a health expert on TV, including on the Today Show and Good Morning America.Anna serves as a writing coach for the New York Writing Room and is on the board of the Deadline Club, the New York chapter of the Society of Professional Journalists. Anna studied psychology and gender and health at the University of Michigan, where she graduated with high honors in 2009. She earned her master's in interactive journalism from American University in 2014. She's completed two marathons, four Olympic-distance triathlons, and one half-Ironman triathlon. Follow her on Twitter, Facebook, LinkedIn, and Instagram. Email her at amiller@bjinnox.com.
