The post-workout meal is part of the “bodybuilding canon,” so to speak.
If you’ve been lifting for any period of time, you’ve heard the story:
If you don’t eat protein and/or carbs after training, so it goes, you will either a) impair muscle growth or b) miss out on an opportunity to accelerate it.
Furthermore, meal timing is often stressed.
That is, it’s often claimed that there is a post-workout “anabolic window” in which you must eat your food. If you miss this window, you either lose or miss out on additional gains.
How true are these bodybuilding dogmas, though?
Is there scientific evidence to back up the emphasis on the post-workout meal, or is much of it bunk like many other once-cherished pieces of gymlore?
Let’s find out.
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Table of Contents
When you work out, you start a process whereby muscle proteins are broken down (technically known as “proteolysis“).
This effect is mild while you’re training, but it rapidly accelerates thereafter. If you’re training fasted, proteolysis (muscle breakdown) is even greater, and especially around 3+ hours after training.
Now, muscle breakdown isn’t inherently bad, but when it exceeds the body’s ability to synthesize new proteins, the result is muscle loss. Conversely, when the body synthesizes more protein molecules than it loses, the result is muscle growth.
The goals of post-workout nutrition is minimizing post-workout muscle breakdown, and stimulating protein synthesis. These two effects result in greater total muscle growth.
Now, the question is can post-workout nutrition actually deliver on those goals? And if so, how do you get there?
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The primary benefits of post-workout protein are as follows:
A study conducted by the University ofTexas makes this clear. Researchers had subjects perform heavy leg-resistance training followed by the slow (over the course of several hours) ingestion of either a placebo, a mixture of essential and non-essential amino acids, or a mixture of just essential amino acids.
The result was the group that drank the placebo showed a negative muscle protein balance several hours after their workouts (that is, they were losing muscle), whereas the groups that ingested the amino acid mixtures showed a positive balance (they were building muscle).
While this may seem like a minor benefit, it adds up over time.
Every day that you give protein synthesis rates a little boost, you build a little more muscle than you would have otherwise built. Over the course of several months, or years, those few grams extra here and there can turn into pounds of additional muscle built.
You’ve probably heard that protein stimulates protein synthesis, but research has shown that protein eaten after a workout has extra “oomph” in this regard.
This was demonstrated by a study conducted by the Shriners Burns Institute. They took 6, normal untrained men and intravenously infused them with a balanced amino acid mixture both at rest, and after a leg workout. The post-workout infusion resulted in 30-100% more protein synthesis than the at-rest infusion.
A study commonly cited in connection with post-workout protein needs showed that 20 grams of post-workout protein stimulated maximum muscle protein synthesis in young men. That is, eating more than 20 grams of protein after working out did nothing more in terms of stimulating muscle growth.
That said, we can’t really assume that this 20-gram number applies to everyone. Protein metabolism is affected by several things:
On the other hand, elevated levels of cortisol reduces protein synthesis and accelerates the process whereby the body breaks down amino acids into glucose (gluconeogenesis), thereby reducing the amount available for tissue generation and repair. Some people have chronically elevated cortisol levels, and this impairs protein metabolism.
So, while 20 grams of protein might be enough to stimulate maximal muscle growth under certain conditions, this won’t hold true for everyone.
Some people will need more to reach the same level of synthesis, and others will be able to benefit from more protein (it will result in more protein synthesis).
Personally, I eat 40-50 grams of protein in my post-workout meal to ensure that I am stimulating maximum protein synthesis.
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The most common reason we’re told to eat carbs after training is to “spike insulin levels,” which is supposed to really kick muscle growth into overdrive.
This isn’t entirely accurate.
Insulin doesn’t directly induce protein synthesis like amino acids do, but it does have anti-catabolic properties.
That is, it decreases the rate of protein breakdown that occurs after exercise. And as muscle growth is nothing more than protein synthesis rates exceeding protein breakdown rates, anything that increases the former and decreases the latter improves this “equation” in our favor.
A good example of this at work is a study conducted by McMaster University that compared the effects of high- and low-carbohydrate dieting with subjects engaging in regular exercise. Researchers found that subjects following the low-carb diet had increased protein breakdown rates and reduced protein synthesis rates, resulting in less overall muscle growth.
These effects, however, level off around 15-30 mU/L, or about 3-4 times the normal fasting insulin levels. “Spiking” insulin levels higher than this doesn’t deliver more “protein sparing” effects.
And it turns out that you don’t even need to eat carbs to reach such a level–you can do it with protein alone. One study showed that the insulin response to the ingestion of 45 grams of whey protein peaked at about 40 minutes, and these levels were sustained for about 2 hours.
If you include carbs with your post-workout meal, however, insulin levels will rise faster, and remain elevated longer. One study showed that the ingestion of a mixed meal containing 75 g carbs, 37 g protein, and 17 g fat resulted in an elevation of insulin levels for over 5 hours (at the 5-hour mark, when researchers stopped testing, insulin levels were still double the fasting level).
So, this is one reason to include carbs in your post-workout meal: to quickly raise insulin levels and keep them elevated for longer periods of time.
Another reason relates to a substance known as “glycogen,” which is a form of energy our body produces from carbohydrate, and which is stored primarily in the liver and muscles.
If you’re weightlifting, keeping your muscles as full of glycogen as you can is important. It improves performance, and research has shown that when muscle glycogen levels are low, exercise-induced muscle breakdown is accelerated.
Now, anaerobic exercise like weightlifting causes marked reductions in muscle glycogen stores, and when your body is in this post-workout glycogen-depleted state, its ability to replenish glycogen stores is greatly increased. In this state, your muscles can “supercompensate” with glycogen, meaning they can store more than they had before the depletion.
This “supercompensation” gives you a nice post-workout carb pump, but it won’t likely affect your workout performance unless you’re engaging in multiple bouts of intense exercise in the same day. So long as you eat enough carbs throughout the day, your body will eventually fill its glycogen stores back up.
That said, the post-workout depleted state does create a nice “carb sink,” which you can use to enjoy a large amount of carbs with little-to-no fat storage (as the body will not store carbohydrate as fat until glycogen stores are replenished).
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So, in conclusion, carbs are worth including in your post-workout meal to keep insulin levels elevated longer, and because it’s a great time to enjoy a nice big meal.
When the subject of post-workout nutrition comes up, it almost always includes opinions on the idea of an “anabolic window.”
The theory of the “anabolic window” is that you have a “window” of time after your workout to eat food, and if you do this, you muscle growth is accelerated. If you don’t however, you will miss out on this benefit, or even worse, lose muscle.
How true are these claims, though?
Well, research indicates that protein ingested within 1-2 hours of finishing a workout may increase muscle growth.
For example, a study conducted by Bispebjerg Hospital had 13 untrained elderly men follow a 12-week resistance training program. One group received an oral protein/carbohydrate supplement immediately post-workout, while the other received the same supplement 2 hours following the exercise bout.
The result: the post-workout ingestion group built more muscle than the 2-hour-later ingestion group.
A well-designed and well-executed study conducted by Victoria University is also worth reviewing. It was conducted with 23 recreational bodybuilders that were to follow an intense weightlifting program for 10 weeks, and were divided into two groups:
After 10 weeks, researchers found that group 1 (pre- and post-workout consumption) built significantly more muscle than group 2 (morning and evening consumption).
On the other hand, there are studies that have failed to show any meal timing benefits, such as this, and this (although the latter study used DEXA to assess body composition, which isn’t sensitive enough to detect small changes in muscle size).
Considering the research we have available, I advise you eat protein within 1-2 hours of completing your workout, as there’s a good chance that it will help you build more muscle than if you skipped such a meal.
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There’s a wide variety of post-workout pills and powders out there, and all are sold on the basis of improving recovery and/or accelerating muscle growth.
Instead of running through the list of all the types out there, let’s keep it simple.
Here are the only supplements I think are worth taking post-workout:
If you use a recovery supplement, you can take it post-workout, but I don’t know of any research that indicates timing is important with amino acids like glutamine and L-carnitine (two common “recovery” aminos people take).