Anabolic Window: Fact or Fiction

Anabolic Window: Fact or Fiction

What Exactly Is The Anabolic Window (And When)

If you’ve been training for a while you might have heard somebody advise you that you need to take a protein shake immediately after a workout. Otherwise, they say, your muscles will not grow. If the person telling you this was particularly well informed they may have told you that this was known as the Anabolic Window.

The Anabolic Window sounds quite exciting as a name, to be honest anything with the prefix Anabolic sounds intriguing due to Anabolic Steroids. But Anabolism is just a word for building complex chemical compounds such as protein from smaller compounds such as amino acids. It is used for growth and repair in the muscles.

But does the Anabolic Window even exist? The answer is rather complex, and this article will strive to clear up any misunderstandings that you may have.

The importance of Protein

When you exercise, you are essentially breaking your muscles down to build them back up, bigger and stronger than before. Each contraction of the muscle will cause tiny micro-tears in the muscle fibre. Your body will repair these micro-tears through a process called Muscle Protein Synthesis.

To allow Muscle Protein Synthesis to occur your diet needs to contain additional protein, this is why athletes require almost twice as much protein as a sedentary individual [1]. After exercise Anabolism (muscle growth) can occur for up to 48 hours, but for this to happen there needs to be a positive Muscle Protein Net Balance [2].

This is why the Anabolic window theory became popular, if exercise lowered protein (when breaking down the muscle fibres) surely extra protein would have to be added immediately? And when studies were taken on athletes in a fasted state this was the case. If the athlete hadn’t eaten anything and then exercised the protein required for growth and repair would not be available.

If you are training fasted then immediate protein/carb intake should be a priority, this is because muscle protein synthesis and muscle protein breakdown increase after exercise, this will use up your stores of amino acids (protein) and as such you will need to increase protein to restore a positive net protein balance [3].

But how often does anyone train in a fasted state? Sure it does happen (in which case, there is an anabolic window of sorts) but the majority of gym goers have eaten normally beforehand – and plan to eat normally afterwards.

The importance of a normal diet

What’s interesting to note, is that in studies where participants had a higher than average intake of protein per day, consuming protein immediately pre/post workout had no effect on performance or on body composition [4].

This led to many people believing that total protein intake per day was much more important than nutrition timing (i.e. taking protein at a certain point pre or post workout). But a study by Alan Aragon and Brad Schoenfeld (2012) found that whilst total daily protein intake was important, meal timing was also crucial [5].

When they looked into the Anabolic Window, they found that so long as the participant consumed a high-protein meal an hour or two before a workout, the protein would still be being absorbed during and after the workout.

So there would be no need for a pre-workout or post-workout shake, or even a peri-workout drink (a lot of gym-goers spend their money on amino acid drinks) so long as you have eaten well beforehand.

So what should I be doing?

If you exercise first thing in the morning then grabbing a protein shake beforehand, and having protein and carbohydrates afterwards is a perfectly sensible move. This will ensure you have a positive Muscle Protein Net Balance, which will ensure your muscles can grow bigger and stronger.

For you, the Anabolic Window does exist. If however you have time for a proper breakfast first, or you train after lunch then there is no need for additional protein. Your breakfast (so long as it is high in protein) should be more than enough, and your next meal – provided it is within two or three hours max of the workout should help with recovery.

If you have dinner before a workout, then you will want to eat a high-protein snack, or take a protein shake before going to bed.

Conclusion Regarding the Anabolic Window

There is an Anabolic Window, but it is much larger than people believe. It is also a lot easier to avoid, so long as you are eating properly. Sadly, this is another nail in the coffin for those who believe that training in a fasted state is somehow superior to regular training. If anything, fasted exercise is a poor substitute.

In a review of the effectiveness of fasted cardio for fat-loss, Brad Schoenfeld stated that there would be no benefits to this over training after a meal. He went on to say that “the strategy has potential detrimental effects for those concerned with muscle strength and hypertrophy” [6].

The trick with any nutritional strategy is to try and keep it as relevant to your lifestyle as possible, if you have always trained at 5am then keep doing so, but alter your diet accordingly. If you want to train between lunch and dinner, then that’s fantastic. Don’t worry about consuming your post-workout shake afterwards, unless you struggle to hit your daily protein targets without it.

If you’ve always taken your protein shake after a workout, then by all means keep doing so. There are lots of benefits, just don’t stress out if you can’t get to it in time! You’re muscles aren’t going to catabolise themselves.

Stop stressing about what time you eat your meals, live a normal life, and train hard. You’ll get the results you want so long as you are consistent.



[1] Tarnopolsky, M., Atkinson, S., MacDougall, J., Chesley, A., Phillips, S., Schwarcz, H. 1992. Evaluation of protein requirements for trained strength athletes. Journal of Applied Physiology 73(5): 1986-95

[2] Phillips, S., Tipton, K., Aarsland, A., Wolf, S., Wolfe, R. 1997. Mixed muscle protein synthesis and breakdown after resistance exercise in humans. American Journal of Physiology 273(1 pt.1): E99-107

[3] Kumar, V., Atherton, P., Smith, K., Rennie, M. 2009. Human Muscle Protein Synthesis and breakdown during and after exercise. Journal of Applied Physiology 106(6): 2026-2039

[4] Hoffman, J., Ratamess, N., Tranchina, C., Rashti, S., Kang, J., Faigenbaum, A. 2009. Effect of protein-supplement timing on strength, power, and body-composition changes in resistance-trained men. International Journal of Sport Nutrition and Exercise Metabolism 19: 172-185

[5] Aragon, A., Schoenfeld, B. 2012. Nutrient timing revisited: is there a post-exercise anabolic window? Journal of the International Society of Sports Nutrition 10(5)

[6] Schoenfeld, B. (2011) Does Cardio After an Overnight Fast Maximise Fat Loss? Strength & Conditioning Journal 33(1): 23-25