Post Workout Protein and the Anabolic Window

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post workout protein

I remember it so well. Every time I would pack my gym bag before heading off for a workout, I would always be sure to include my post workout protein shake.  It would be ready mixed in my shaker bottle, ready to be slammed back as soon as I finished the session.  And on the odd occasion when I forgot to pack my protein shake, I would be horrified!

I would hurry home as fast as I could, to quickly get my protein down as fast as possible.  My eyes would be on my watch, as I raced the clock to consume my post workout protein shake within 45 minutes of finishing my workout.  Because if I didn’t get my protein in time, that gruelling workout I had just put myself through would be a total waste.  It would result in no muscle gain if I didn’t have protein within the 45-minute post workout anabolic window!  Little did I know that I had nothing to panic about!

The 45-minute post workout anabolic window

It used to be treated as gospel that in order to maximise muscle gains, you have to consume protein within 45 minutes of completing a resistance training workout.  This time frame is known as the “anabolic window”.  We now know that the “anabolic window” isn’t anywhere near as small, or as important, as we first thought.

Yes, post workout protein can help your muscles recover and grow.  And logically, since we know that protein is used by the body for growth and repair, it sounds like it makes sense to fuel your body with nutrients after having broken your muscle tissue down through hard training.  But still, this 45-minute period of panic isn’t the drastic affair we first believed.

It’s all about total daily protein intake

A meta-analysis by Schoenfeld et al considered23 high-quality studies on protein timing.  They concluded that the total amount of protein consumed each day was a lot more important for muscle growth, as opposed to “when” that protein was consumed.

The anabolic effects of protein last 5 – 6 hours

There is evidence to show that the muscle building effects of ingested protein actually last for 5 to 6 hours.  

Let’s put this into a real-life scenario.  

You have lunch (which includes a healthy serving of protein) at 1pm.  Work finishes at 5pm and get to the gym for 5.30pm, to workout for an hour.  You finish your workout at 6.30pm.  In this case, it would make sense to have a post workout protein shake, since it would have been 5 and half hours since your last protein intake.

Post Workout Protein

But, let’s look at another example.

You wake up, slam down a protein shake, and head straight to the gym for an early morning workout before work.  Say you have your protein shake at 7am, get to the gym for 7.30am, and finish training at 8.30am.  There would be no need to necessarily have a post workout protein shake immediately. You could simply wait up until lunch at 1pm, which is 6 hours after your morning pre-workout protein shake (as long as your lunch includes a healthy dose of protein).

Protein shakes aren’t necessary

Note that protein shakes are certainly not necessary either, they simply can act as a convenient means of meeting your protein requirements.

And off course, how frequently you consume protein throughout the day is entirely up to you.  Whether you have just 3 meals, or decide to have 6 meals, it is your choice.  As long as you go no longer than 6 hours without ingesting protein, your body will still have protein “in your system” to build muscle!  Just focus mainly on getting enough protein in total over the course of each day. Don’t fuss over “having” to necessarily take in protein immediately after working out.

How much protein do I need each day?

Research suggests that, if you are looking to build muscle and you are regularly resistance training, you should aim for at least 1.6 to 2.2 grams of protein per kilogram of bodyweight each day.  So basically, aim for 1g of protein per 1lb of bodyweight each day minimum.  It still seems to be unclear what the upper limit for daily protein intake is.  But we do know that there is no proven harm in taking in “extra” protein.

post workout protein

The take home message

  • Focus on consuming “enough” protein in total, over the course of each day.
  • Aim for at least 1g of protein per 1lb of bodyweight each day in total.  But more protein than this is fine too.
  • Protein will continue to have anabolic (muscle building) effect for 5 – 6 hours after consuming it.
  • Having protein immediately after working out, i.e. the 45-minute anabolic window, is not necessary.
Post Workout Protein


International society of sports nutrition position stand: diets and body composition
Alan A. Aragon, Brad J. Schoenfeld,Robert Wildman, Susan Kleiner, Trisha VanDusseldorp, Lem Taylor, Conrad P. Earnest, Paul J. Arciero, Colin Wilborn, Douglas S. Kalman, Jeffrey R. Stout, Darryn S. Willoughby, Bill Campbell, Shawn M. Arent, Laurent Bannock, Abbie E. Smith-Ryan and Jose Antonio
Journal of the International Society of Sports Nutrition201714:16
©  The Author(s). 2017Received: 25 May 2017Accepted: 30 May 2017Published: 14 June 2017

Lou Schuler and Alan Aragon, “The Lean Muscle Diet: a customized workout plan – eat the food your love to build the body you want and keep it for life”, Men’s Health, Rodale Inc.(2014).

de Souza R, Bray G, Carey V, Hall K, LeBoff M, Loria C, et al. Effects of 4 weight-loss diets differing in fat, protein, and carbohydrate on fat mass, lean mass, visceral adipose tissue, and hepatic fat: results from the POUNDS LOST trial. Am J Clin Nutr. 2012;95(3):614–25.

Antonio J, Peacock C, Ellerbroek A, Fromhoff B, Silver T. The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals. J Int Soc Sports Nutr. 2014;11:19. doi:10.1186/1550-2783-11-19.

Antonio J, Ellerbroek A, Silver T, Orris S, Scheiner M, Gonzalez A, et al. A high protein diet (3.4 g/kg/d) combined with a heavy resistance training program improves body composition in healthy trained men and women–a follow-up investigation. J Int Soc Sports Nutr. 2015;12:39.

Antonio J, Ellerbroek A, Silver T, Vargas L, Peacock C. The effects of a high protein diet on indices of health and body composition–a crossover trial in resistance-trained men. J Int Soc Sports Nutr. 2016;13:3. doi:10.1186/s12970-016-0114-2.

Antonio J, Ellerbroek A, Silver T, Vargas L, Tamayo A, Buehn R, et al. A high protein diet has no harmful effects: a one-year crossover study in resistance-trained males. J Nutr Metab. 2016;2016:9104792. doi:10.1155/2016/9104792.

The effect of protein timing on muscle strength and hypertrophy: a meta-analysis
Journal of the International Society of Sports Nutrition201310:53
©  Schoenfeld et al.; licensee BioMed Central Ltd. 2013
Received:22 September 2013,Accepted:20 November 2013

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