Getting a good meal of carbs and protein after your workout is a great way to fuel yourself and support your goals, whether you’re training for strength, endurance, or both. But what if you don’t have the perfect post-workout meal lined up? Is your workout wasted?
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You can’t “waste” a workout
Before we get into whether the “anabolic window” is real, we need to address a pervasive myth: People will tell you with a straight face that you’re “wasting” your workout if you don’t fuel properly before or after.
There is no such thing as wasting a workout. I literally cannot imagine a way to cancel out the effects of a workout. Exercise triggers many adaptations within our bodies: It puts processes into motion that build muscle, adjust the sensitivity of our cells to insulin, helps manage our mental health, and more. Exercising without eating properly is like having Christmas when the Grinch stole some presents—it may not be everything it could have been, but the important stuff still happens.
But does skipping a post-workout meal (or even eating something you’d categorize as junk food instead of something “optimal”) really constitute poor eating? Not really.
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What happens in that post-workout window
The 30 minutes after a workout (or 15 minutes, or two hours, depending on who you ask) have sometimes been dubbed the “anabolic window” or “metabolic window.” You’ll also hear different versions of this idea depending on whether you’re talking to lifters (who are interested in eating protein and building muscle) or endurance athletes (who are most interested in eating carbs to replenish muscle glycogen). The two ideas are connected, though, and most of us would be best off eating a meal or snack that includes both protein and carbs.
The “anabolic window” is probably a myth
It’s not a crazy idea to think you might grow more muscle if you eat protein after a workout. Strength training triggers an uptick in muscle protein synthesis (MPS), and so does eating protein. If we stack those two events, the thinking goes, maybe we’ll send an even bigger signal to the body to build muscle.
There are a few studies that seem to support this idea, but the last few decades of research have failed to prove that the anabolic window exists at all. Nutritional research can be a bit weird because it’s trying to separate out the effects of different factors. You’ll have people drinking specific shakes while not eating anything else, and then researchers will look for signs of MPS at certain time points. That’s very different from the real-world question of “if I always have a shake after I work out, will I be more jacked in a year than if I don’t?”
In a 2018 review of the evidence, exercise physiologist Brad Schoenfeld wrote that “any effect of protein timing on muscle hypertrophy, if in fact there is one, is relatively small. Total daily protein intake is by far the most important factor in promoting exercise-induced muscle development.” He adds that as long as you had a meal within three to four hours before your workout, when you eat afterward is not that important.
If you want a specific prescription, he gives some numbers: Ideally you’ll have a pre-workout meal and a post-workout meal that each contain 0.4 to 0.5 grams of protein per kilogram of bodyweight (so, 30 grams if you weigh 130 pounds, 45 grams if you weigh 200 pounds) and you’ll make sure those meals are no more than six hours apart. In other words, you could have lunch at noon, work out sometime in the afternoon, and have dinner at six. No special shakes needed.
The “glycogen window” is real, but most of us can ignore it
So what about carbs for endurance athletes? There is a small effect of timing here, but you don’t need to worry about it unless you plan to do a second workout in fewer than 24 hours. There are a few other factors, too, but we’ll get to those.
The issue here is glycogen, our body’s storage for carbohydrates. We use glucose to fuel high-intensity training, and to supplement fat burning in low intensity training. If you eat before a workout—say, you have breakfast before you go for a run—your body will just use the glucose that comes from your gut via your blood. In other words, blood sugar is your fuel.
But our muscles each have their own store of glycogen, which is a storage form of carbohydrates. We don’t have much glycogen, and it’s possible to burn through our stores in a single, very long workout or in a series of workouts where we don’t replenish it in between. When you’re running low on glycogen and you have low blood sugar, you can feel fatigued. This is why marathoners eat snacks and sports drinks (and suck down those gross little packets of gel) while they’re on the run. It’s also why powerlifters bring candy to the gym. Well, that and the fact that you simply can’t have a bad day while you’re eating Sour Patch Kids.
Right after a workout, our muscles are hungry for glycogen, and we can replenish those stores quickly with a snack right after our workout. Anything sugary or starchy will do.
But if you don’t replenish your glycogen right away, what happens? Here’s the good news: It gets replenished anyway as you eat your normal meals throughout the day. The post-workout meal is a shortcut, not a one-time-only opportunity.
So should you replenish glycogen after a workout? Yes, if you plan to do another workout soon (like later that day), and if you won’t be able to eat right before or during that other workout, and if you care very much about your performance and your fatigue levels during that next workout. If you’re an athlete who regularly does two-a-days, you probably want to get into the habit of eating some carbs after each workout. The rest of us don’t need to worry about it as much.
If you don’t have healthy options, it better to eat junk food or nothing?
So we’ve established that post-workout meals are helpful for endurance sports, and maybe slightly helpful for strength workouts, but that either way they’re not crucial to your gains so long as you’re eating well all day long. But there’s another question that I’ve heard a few times: if I want to eat a post workout meal, but I don’t have the perfect meal available, is it better to eat cookies or fast food or something, or to eat nothing at all?
In that case I would say: Eat the convenient thing, unless it will mess up your nutrition for the day. A burger is still going to provide plenty of protein (from the meat) and carbs (from the bun). Being tasty does not mean it’s automatically unhealthy.
If you only have cookies or candy available, those will replenish your glycogen just fine, but you should be aware that they’re not doing anything for your protein needs. In fact, chocolate milk has a reputation as a recovery drink because it’s a convenient source of both protein and carbohydrate. (There is nothing special about it otherwise.)
Ultimately, what matters is whether you’re getting enough protein over the course of the day, and whether you have carbs when you need them—either by eating them before or during a workout, or having glycogen in your muscles ready to go. Whether the food is “healthy” doesn’t really enter into it, performance wise. You should still eat your vegetables, but they can wait until another meal.