The Rules of Protein Timing Are Changing—According to New Science (2025)

This story is part of a series on navigating the new world of peak protein, from the latest packaged products to emerging research. Read the rest of the stories here.

IF TRYING TO load up on all the protein you need every day is feeling like a chore, new science might provide some relief.

For a long time, the thinking was that your body could only use about 20 grams of protein at a time because it can’t store protein the way it can store carbs and fat. Your body would, however, take in the amino acids from that 20 grams and use them to make valuable, strength-building proteins in your muscles. Anything above that? Your muscles would snub it and that protein would just be calories.

That meant giving yourself a steady, slow drip of protein. And depending on which protein recommendations you’re paying attention to, that approach could mean dumping 20 grams of protein into your body five to eight times a day. Every day. (And you thought it was the lifting that was exhausting.)

But some emerging research suggests you don’t have to be that strict—thank goodness. Here’s the truth about what your body does with protein and when.

Does Protein Timing Matter?

SORT OF.

Yes, it’s great if you consume protein around the time you do your workout. “Exercise temporarily sensitizes skeletal muscle to the provision of amino acids,” says James McKendry, PhD, who runs a research lab on muscle and nutrition at The University of British Columbia.

In other words, muscles are a little more eager to take in those amino acids after exercise than they are if you’ve just been sitting around. But getting in your post-workout shake doesn’t have to be an emergency situation. Your body is more accommodating than that, at least according to a recent study.

Luc van Loon, PhD, professor of physiology of exercise and nutrition at Maastricht University, and his team, wanted to find out how capable the human body is of using larger amounts of protein over longer periods of time. In a small study published in Cell Reports Medicine, the researchers gave people 100 grams of protein and then monitored their muscles for far longer than the usual four to six hours—to upwards of 12 hours. “We saw that actually, if you give more protein, you get a more prolonged stimulation of muscle protein synthesis,” he says. In other words, their muscles kept productively using that protein long after they’d eaten it.

What if you could eat more protein on days you lift heavy and then take the stress off all that protein prioritizing on days you don’t? Well, you kind of can.

“That doesn’t mean we’re telling everybody to ingest 100 grams of protein with each main meal,” he says. “But you don’t have to worry too much about missing a meal or missing your protein. In fact, if you perform exercise, you will get a greater response in muscle building from every meal you ingest up to 24 hours later,” he says.

The team even looked into whether eating lots of protein one day might render your muscles “full,” so to speak, and not as excited about taking up more amino acids and synthesizing protein the next day. “That didn’t seem to be the case,” he says.

One important point: “Protein synthesis” doesn’t mean “big muscles."

Muscle protein synthesis generally means your muscles are aiming to make themselves better in some way—bigger, stronger, able to endure more stress. But be aware that van Loon’s study tagged the building blocks of this process (amino acids) and measured how much incorporated into the subjects’ muscles. “You can see if uptake is high or low after you exercise and after you eat,” van Loon says, “But it doesn’t tell you anything about whether there’s a net increase in muscle mass.”

When Should You Eat Protein for Muscle?

AS VAN LOON’S research suggests, “when” is adjustable.

“Provided that your low days aren’t excessively low [below 0.8 g/kg/day] and your average daily intake is close to the recommended amount for hypertrophy—in the range of 1 to 1.8 g/kg/day—coupled with exercise training, I doubt there would be a significant difference in adaptation,” says McKendry.

So yeah, you can do, say, 1.6 g/kg on days you lift heavy and get 0.8 g/kg on days you don’t. Or, you can just do 1g per gram of target body weight every day. Whatever works for you.

Just remember what Stuart Phillips, PhD, distinguished professor in the department of kinesiology at McMaster University, says about muscle building: “Exercise bakes the cake; protein is the icing. Going to the gym and lifting consistently are far more important than protein.”