Not Building Muscle? Protein Might Be the Issue — Here's When to Eat It, According to an RD

What and when to eat protein around a workout (before? after? during?) isn't exactly the world's biggest debate. But the more you start working out and trying to build muscle — and the more you see people walking around the gym shaking up their protein drinks — it's certainly something you get curious about. Protein is essential if you're trying to build muscle, but does it really matter when you eat it?

According to Michele Fumagalli, a registered dietitian with Northwestern Medicine and a professional CrossFitter, the timing comes down to two factors: muscle breakdown and possible stomach upset.

Why Is Protein Necessary For Muscle Gain?

The reason people associate protein with muscle building in the first place, Michele explained, is because of what happens when you don't eat it. The way you build muscle is actually by breaking it down, creating tiny tears in the tissue, then rebuilding it bigger and stronger. But that's only possible if you give your muscles the nutrients that allow them to grow, and protein, which is brimming with amino acids, is the compound that does that best.

Should You Eat Protein Before a Workout?

That brings us to the timing questions. You can get pretty deep into the details of when and what exactly to eat before a workout (here's an in-depth breakdown), but here's a good rule of thumb: the closer you get to your workout, the more you should stick with foods that are easily digestible.

"Two-and-a-half to three hours before a workout is kind of when you want to have your last meal," Michele told POPSUGAR — a full meal with carbs, protein, and a little bit of fat. About an hour out from a workout, if you're hungry, she said you should stick with carbs and a small amount of protein, like a banana with a tablespoon of peanut butter or a Nutri-Grain bar. Right before the workout — half an hour out, or less — you'll want to stick with straight carbs and some sugar; Michele suggested applesauce: sweet and easy to digest.

Why not load up on protein right before a workout? It has less to do with muscle gains and more to do with workout discomfort. Protein is harder to digest than carbs, so your body sends blood to your stomach to help break it down. But when you exercise, that blood gets diverted to your muscles, "because those are what we're exhausting and we're using," Michele said. Having heavy protein- and fat-rich foods in your stomach when the blood gets called away can cause stomach upset, making for an uncomfortable and often underperformed workout, which can hurt your muscle gains.

Should You Eat Protein After a Workout?

As for protein after your workout, Michele said that's essential for preventing muscle breakdown, especially if you haven't eaten for over three hours beforehand (and even if you're not hungry). Throw in some carbs, too, to replenish your supply of glycogen (stored glucose, which your body gets from carbs) that got used up during the workout. But, Michele added, the post-workout protein isn't as necessary if you ate more recently. "If you had a pre-meal maybe two hours, two-and-a-half hours prior, your body's using that protein and the carbohydrate that you ate to fuel yourself during the workout and recover afterwards," she said.

The protein and carbs you eat afterwards will supplement that process but aren't quite as crucial as if you'd done a fasted workout; then you'd have to be more strict to prevent muscle breakdown. A 2003 study showed that both muscle synthesis and breakdown spike an hour and a half after a workout — meaning that your muscles are primed for growth but can also go the opposite way without proper refueling.

The main takeaway: you're good to eat protein before a workout, as long as it's far enough in advance to avoid GI stress — aim for an hour out, at the latest. The after-workout protein will be more crucial, particularly if you do a fasted workout (not eating for three or more hours before, or working out first thing in the morning without breakfast). Whatever you do, Michele said, remember that these are just two snacks out of a full day of eating. Eating a healthy balance of carbs, protein, and fat throughout the day, not just around a workout, will also boost your muscle gain and keep you healthy and energized.

Wondering what kind of protein is the best? Michele recommends protein shakes if you need a quick, convenient option but says food sources like chicken are best, if you can get one. Check out a full list of the best protein sources, and pick your poison.