Talk to most long-term gym goers, and they will tell you that one of the most important meals of the day is the post-workout protein shake (or high protein meal). The established belief is that you need to take post-workout protein immediately if you want your muscles to grow, neglecting this will lead to catabolism or “loss of gains, and studies This period is known among lifters as the “Anabolic Window” or window of opportunity.
But how long is this window, and how vital is it to take post-workout protein? Is there science behind it, or is it another example of supplement companies creating a problem that doesn’t exist? This article will address these issues by looking at what the science says.
Muscle Protein Synthesis
Before discussing the anabolic window, we need first to define what it is. Anabolism is the process of creating complex tissue from simple components in the body, so increasing muscle fibres from protein intake is an anabolic process. With regards to muscle, protein is used to increase muscle fibre size and strength using a process called Muscle Protein Synthesis.
When you work out, you perform hundreds of muscular contractions.
Doing so causes micro-tears in muscle fibres. The more you overload the muscle, the more muscle fibres are recruited, and the more muscle damage is created. Once you have finished the exercise, your body can begin the process of repairing the muscle damage and rebuilding the muscle fibres so that they are stronger and larger.
To do this the body requires amino acids, particularly Leucine. These amino acids are found in protein. The amino acids are transported to the muscle fiber cells where they begin protein synthesis. The more protein you have in your system (up to a certain point) the more protein synthesis can occur. Likewise with exercise, the more you have worked the muscle, the more that muscle can grow and strengthen.
Other factors play a part in muscle protein synthesis, sleep, cortisol levels, testosterone levels, growth hormone levels, and training level. But the primary factor is protein intake.
Now we know why protein is necessary for protein synthesis, we can look at how the timing of it can affect growth – or whether it does at all? You might be thinking that if protein is necessary for muscle growth then surely post-workout is the best time to have it. You’ve just come out of a workout, and your muscles are already beginning the process of repair.
But this has not been found to be the case, studies consistently show that it’s not the timing of the protein that matters, but rather the total protein intake for the day. In a 2013 study by Schoenfeld, Aragon, and Krieger it was found that total protein intake was the biggest factor in muscle growth . The study concluded that:
these results refute the commonly held belief that the timing of protein intake in and around a training session is critical to muscular adaptations and indicate that consuming adequate protein in combination with resistance exercise is the key factor to maximising muscle protein accretion.
Another study by Aragon & Schoenfeld (2013) reviewed the relevant literature on the anabolic window, and they found that the reason that there had been so much initial evidence for a post-workout window was that the majority of studies had been performed on fasted athletes.
This means that the athletes had not eaten anything before performing their sessions. In the studies that had pre-workout protein intake, the anabolic window was less relevant. This is because the body is “capable of sustaining amino acid delivery into the post-exercise period” , meaning that a pre-workout meal can keep your body filled with protein for hours afterwards, eliminating the need for a post-workout protein shake.
So what does this mean for me?
This means that hitting your daily protein target is the most important factor in getting bigger and stronger muscles. If you are supposed to eat 155g of protein per day then as long as you hit that target it doesn’t make too much of a difference when exactly you are consuming it. Now this does come with a couple of caveats: Firstly, you would still want to have a pre-workout meal inside you about an hour before training.
Secondly, if you are training fasted (which has been proven to be an ineffective method for fat loss)  then you do require a post-workout protein shake. This is because you don’t have any amino acids in your system as you’ve not eaten for at least 8 hours (possibly as many as 12). Kumar et al. found that immediate post-exercise protein and carbohydrate intake were necessary for boosting insulin and stimulating muscle protein synthesis .
Another caveat is that while post-workout protein may not be necessary, that doesn’t mean that you shouldn’t try and spread your protein intake out. Mamerow et al. (2014) found that the majority of people tend to take most of their protein at dinner time . The study went on to say that for optimal MPS you should spread out your protein throughout the day.
The best option is to eat three high protein meals per day (Breakfast/Lunch/Dinner) and try to time your workouts around that. If you can’t manage it (due to work, family, or other constraints) then ensuring that you at least have a protein shake or snack before a workout is a good idea.
Steps to Success
Here is a list of things that you need to do to ensure that you are creating the perfect environment for increased muscle size and strength. Remember it is unlikely that you will be able to get everything perfect all the time, but you’ll still get good results anyway – just from being consistent.
1. Find out your ideal protein intake
Your ideal protein intake will be different depending on who you are or what your goals are. However, for most people who are considering building muscle the following advice taken from Helms, Aragon, & Fitschen (2014) is probably the most useful .
You should be aiming to hit between 2.3 and 3.1g of protein per kg of lean body mass (LBM). LBM is your bodyweight minus the amount of body fat you have. So if you weigh 100kg and are 25% body fat, then you have 75kg of lean body mass. If you are a natural bodybuilder, then you’d probably look to the higher end of the spectrum, whilst less experienced lifters should consider 2.3g a better target. Once you have found your target, your number one goal is to ensure that you hit it day in day out without fail.
2. Planning your meals around your workouts
As we mentioned before, try to always ensure that you have a pre-workout meal around an hour before a workout. If that’s impossible (like if you train at 5 am or something), then an immediate post-workout protein shake would be effective. You might also consider a peri-workout shake (BCAAs are always a popular choice).
3. Spread your protein out
You don’t want to be having 70 or 80% of your protein in one meal, so try and spread it out between the three. If you’re supposed to be hitting 155g per day, then look for 40g at breakfast as a minimum. You can still have more at dinner than any other meal, but just make sure that breakfast and lunch are high protein too.
So that about wraps it up, the anabolic window does exist but it is much larger than most people assume, and a lot less important provided you are hitting your daily protein targets. Concentrate on this first, and then you can worry about post-workout shakes, etc …