Protein Post-Workout

When we learn an exercise “rule” early in our fitness journey, it can stick with us for years. The advice for me was to always eat protein within 30 minutes of finishing a workout. I’ve heard it from so many people that I never questioned rushing to drink a glass of chocolate milk or adding some nuts, even when I wasn’t hungry.

But recently, more than one sports dietitian told me that the 30-minute window is a myth (and that it can be different for women vs. men). Yet I kept watching and listening to it again and again. So what is the truth? Well, it turns out there is some value in this piece of nutritional advice. “The reality is that there’s no clear-cut statement that applies to everyone,” says sports scientist Chad Krkcic, Ph.D., associate professor of exercise science at Lindenwood University in Missouri.

Before you force yourself to chug another protein shake as soon as you leave the gym, you should consider this context.

Why do people say you need protein after a workout?

The idea behind eating protein after a workout is basically to take advantage of the “anabolic window,” which is the 30 to 60 minute period after exercise when our bodies are most sensitive to the process of muscle protein synthesis, or building muscle mass. To do this we need protein in our system.

“Our bodies are constantly making and breaking down proteins. And when we exercise, that cycle speeds up,” explains Dr. Krkcic. “Proteins are made up of amino acids. And our bodies don’t store amino acids (as we do with carbohydrates and fats). So providing these amino acids in the form of dietary protein helps replace what’s being lost.”

Eating protein (and carbohydrates) after exercise also affects our immune system. “When we train, our immune system is suppressed,” explains Michelle Arnett, RD, MPH, director of Olympic Sports Performance Nutrition at the University of South Carolina. Once we consume nutrients after we’re done, the immune system gets a signal that it’s okay to start functioning normally again.

FWIW: Carbohydrates also have an anabolic window. If you wait more than an hour to eat carbohydrates after exercise, it will take about 50 percent longer to replenish the glycogen stores that fuel your muscles, according to researcher Bradley Schoenfeld, Ph.D., professor of exercise science at Lehman College in New York. However, this really only matters to endurance athletes who do multiple workouts a day—even if you miss that window, your glycogen stores will return to normal within 24 hours, as long as you’re eating enough normally.

Arguments against instant protein

In 2013, Dr. Schoenfeld led a large meta-analysis that showed that protein timing during training sessions did not make much of a difference in terms of muscle growth. It is a position he maintains even today. “From my reading of the literature, I think we can say with good confidence that any benefits of an anabolic window are minimal,” he says. “There is certainly no evidence that if you don’t do Consume protein, or you’ll miss out on a lot of benefits.

Our muscles are sensitive to protein intake for the full 24 hours after exercise, he says, and just eating protein in all your regular meals (as experts recommend) will do the trick.

“If you’re just trying to be healthy, go to the gym before work, then eat breakfast, or exercise and then eat dinner, half an hour isn’t really that important,” says Kathryn Black, PhD, professor of human nutrition at the University of New Zealand. “It’s the overall protein intake for the day that’s more important.” The American College of Sports Medicine recommends that active individuals consume between 0.5 and 0.9 grams of protein per pound of body weight.

Dr. Kirkcic adds that, really, your actual workout is the more important factor when it comes to building muscle. “If we haven’t reduced our exercise and we haven’t reduced our daily protein intake, the potential for further improvement of the landscape at that time, I would argue, is diminished,” he says. “Some might argue that it has been overturned.”

Who can benefit from protein after exercise?

While the anabolic window may be a bit high for the everyday gym-goer, timing strategies may have small benefits for bodybuilders or elite athletes who perform back-to-back training sessions. People who can benefit from post-workout protein are “those who want to get every last muscle benefit from exercise,” says Dr. Schoenfeld.

Arndt also points out that most athletes already don’t eat enough to meet their energy needs. So, if you tell them not to eat protein after a workout, you’re taking away a potential meal opportunity. “Now you’ve created an even bigger deficit,” she says.

The same holds true for populations such as menopausal and postmenopausal women, where spreading enough protein evenly throughout the day is critical to goals such as muscle maintenance and overall health. She explains that protein needs increase as you age.

So far, it’s unclear whether women’s bodies react differently to protein after exercise. “The research that has been done is not very good, and it’s not large enough for us to draw any firm conclusions,” says Dr. Black. However, respected exercise physiologist Stacey Sims, PhD, theorizes that because women return to baseline more quickly after exercise, and their hormonal status complicates the body’s response to protein, eating near the end of exercise may be more relevant.

Bottom line: Eating protein right after a workout can’t hurt. Arent affirms that there is usually no shortage. But unless you’re trying to land a WNBA contract or win an Ironman, you probably don’t need to be pressed for time. Even if you eat protein a little after your “optimal,” you’ll still get the nutrients your body needs.