“If you don’t drink a protein shake within 30 minutes of finishing your workout, it will be wasted.”
If you’ve done any research on building muscle, then I’m sure you’ve seen this advice.
Fitness “gurus” tell you that there’s a magic “anabolic window” after every workout. They swear that drinking protein during this window is a mandatory part of packing on mass…
But it’s 100% bullshit! And I’ll prove it in this article.
The “Anabolic Window” Myth Explained
Before I break down why this myth is false, let’s start by explaining how it gained traction in the first place.
Here’s the typical logic people use to support the anabolic window:
After you lift weights, your muscle fibers are in a damaged state and your glycogen stores (the carbs your body stores for immediate energy) are depleted…
This part is true. But after that is where the “bro science” comes into play.
…By consuming a mixture of protein and “quick-release” sugary carbs you’re able to super-compensate for these effects by preventing further muscle protein breakdown, spiking muscle protein synthesis, and refilling your glycogen stores. This results in a temporary state where your body can quickly construct new lean mass — the “anabolic window”.
The problem with this theory is that it relies only on simple logic, NOT proven science…
Again, the basis of this theory is true: intense exercise depletes glycogen and breaks down muscle tissue. But using these facts to justify that you MUST consume a mixture of protein and carbs IMMEDIATELY after your workout is making a lot of assumptions.
Below are 3 reasons that prove it simply doesn’t work this way…
Note: If you’re confused what any of these terms mean, keep reading. I’ll explain them all.
Evidence #1: There’s no evidence post-workout nutrition raises muscle protein synthesis
The main purported benefit of the “anabolic window” is that is raises your rates of muscle protein synthesis. This is so important because muscle protein synthesis is the #1 indicator of muscle growth.
..But here’s the thing: the research simply does not support this claim.
In 2013 Alan Aragon and Brad Schoenfeld – 2 top bodybuilding nutrition researchers – conducted an in-depth review of the “anabolic window.” They analyzed and compared every relevant study that has ever been done on this topic.
There is zero conclusive evidence that shows ingesting carbs and protein immediately after a workout raises muscle protein synthesis.
While some studies found a slight benefit, others found a bigger benefit from consuming a pre-workout meal. And to make matters more complicated, many of the studies (both for and against the “anabolic window”) were conducted on elderly individuals, obese people, or populations that don’t regularly exercise.
In other words, there’s no clear benefit to having a post-workout shake. Sure, it may offer slight benefits in some rare cases, but it’s only going to make a negligible difference in the long run.
Evidence #2: Muscle protein breakdown is only an issue if training fasted
Another alleged benefit of the “anabolic window” is to prevent muscle breakdown.
This is accomplished by including simple carbs (e.g. dextrose) in your post-workout shake. You see, simple carbs spike insulin levels. And spiking insulin is proven to slow muscle protein breakdown.
This is important because your body only builds muscle when your rates of muscle protein synthesis (MPS) are greater than your rates of muscle protein breakdown (MPD).
…But here’s the thing: studies show that muscle protein breakdown is only VERY slightly raised post-workout.
In other words, there’s no need to prevent muscle protein breakdown in the first place.
However, there’s one big exception to this rule: fasted training (ie. working out before eating breakfast). If you train fasted, studies show that muscle protein breakdown is significantly raised post-workout.
So, if you train fasted, then you’re in a different category here. In your case, consuming a post-workout shake with protein and simple carbs is actually quite important.
Evidence #3. Glycogen doesn’t need to be replenished right away
The final purported benefit of the “anabolic window” is to replenish your glycogen stores.
Put simply: glycogen is a form of stored carbohydrates in your muscles. It acts as one of the primary sources of energy during your workouts.
And studies show you can use up a lot of your glycogen by the end of a workout. If you want to perform at your best, get stronger, and build muscle, then you want to make sure your glycogen stores are full before every workout.
But here’s the thing: glycogen doesn’t need to be replenished immediately after your workout.
All you need to worry about is refilling your glycogen stores before your next workout, so you can lift as much weight as possible at that time.
And studies show that there’s no difference between consuming carbs immediately post-workout or 2 hours later. In both cases, glycogen levels were exactly the same when measured 8 hours and 24 hours later.
So, unless you’re a competitive athlete who plans on working out again in just a few hours, you don’t need to worry about consuming carbs and replenishing your glycogen stores right away. Just be sure to eat enough carbs as part of your regular diet (especially if you want optimal testosterone levels).
Conclusion: There’s no reason to drink a post-workout shake (unless you trained fasted)
What can we conclude from all of this data?
Simple: there’s no evidence to support the theory of the “anabolic window”.
The exception to this rule is if you train fasted. In this case you should have a protein shake (or a meal) right after your workout in order to prevent muscle breakdown.
If you’re still skeptical, consider this study that examined the long term benefits of drinking a post-workout shake. 33 young men were divided into 2 groups (half had a post-workout shake, half had a placebo). After 12 weeks of lifting, there were no differences in muscle growth between the groups.
If you want to build muscle, you’re better off focusing on eating in a slight caloric surplus and lifting consistently. At the end of the day, a post-workout shake is not going to make any difference.