Does When You Eat Protein Matter After Exercise?

The post workout meal has been touted as critical for affecting gains in muscle and strength. Is that backed up by science? Nope.

Reading studies is hard work! I'm trying to learn to break down super sciency stuff into more simple language, so that you can use science to help you become the person you want to be.

If you don't like longer reads about interesting science involving strength training avert your eyes! This post isn't for you.

This post is about a recent meta-analysis reviewing the effects of protein timing on gains in muscle and strength. A meta-analysis is basically a study about other studies. A meta-analysis or meta uses statistics to combine data from studies so that comparisons can be drawn.

The full meta can be found here for your reading pleasure.

Does When You Eat Protein Affect Your Gains?

The big question that scientists are seeking to answer in research is, how can we get the best results from diet and exercise?

The effect of protein timing on muscle strength and hypertrophy: a meta-analysis was carried out by Brad Schoenfeld, Alan Aragon and James Krieger to see what the body of research said about when you eat your protein.

The short answer is not really. If you want to find out more about the science behind why there isn't a definitive answer and what the authors had to say, read on.

What is the background behind this study?

To this point, it is known that protein consumption is important for increasing muscle mass. The Recommended Daily Allowance (RDA) for protein, 0.8g/kg or 0.36g/lb, is only the minimum amount you need to not get sick. It's been demonstrated here by Lemon et al. that you likely need double that for gains.

There are a number of studies that show protein is important and talk about how much you need to eat. Things that affect this amount include:

  • The quality and digestibility of protein sources
  • How big you are
  • Your age
  • Whether you're pregnant or nursing
  • Whether you're active or not
  • If you're dieting and in a caloric deficit

All of these factors make it hard to get answers to questions like the one we're discussing here today; does when you eat protein matter after exercise?

What are the specific question(s) being asked in the study?

There are two questions being asked in the study:

  1. Does protein timing effect gains in muscle mass?
  2. Does protein timing effect gains in strength?

To be able to answer these questions, there are a lot of variables that need to be accounted for. The researchers handled this problem by selecting good studies and comparing them using a model. The model examined the statistical likelihood that the research behind protein timing is what it says it is.

How was the study carried out?

First, our authors came up with some criteria for what they thought a good study required. They settled on including only randomized control trials and randomized crossover trials. These are some of the most scientifically backed research methods.

Second, the authors individually looked for studies that fit their criteria. A study was deemed quality with the PEDro scale, a valid measure of the methodologic quality of RCTs . Once they both found studies that matched, they checked each others work, to make sure they weren't being biased.

Third, the authors coded and grouped the studies into measures that would impact the results of the study. Some examples of these groups included gender, body mass, training experience, and whether or not the studies matched to total amount of protein that participants in both groups received. The goal here was to be able to compare the size of the effects of each on the overall study results.

Fourth, there were statistical models created in order to be able to calculate the size of the effects and trial results. Results were combined using a scientific method referenced here.

Finally, a statistical analysis was conducted and the results were revealed.

What were the results?

Strength Studies:

  • 478 subjects
  • 96 ESs (effect size)
  • 41 treatment or control groups
  • 20 studies

Hypertrophy Studies:

  • 525 subjects
  • 132 ESs
  • 47 treatment or control groups
  • 23 studies

Does timing have an effect on hypertrophy?

  • Base Model-Yes
  • Full Model-No

Does timing have an effect on strength?

  • Base Model-No
  • Full Model-No

This figure shows a visual distribution of the results of each study for strength along an overall mean using the base model.

Impact of protein timing on strength by study-Basic Model
Impact of protein timing on strength by study
Schoenfeld, Brad, et al. “Figure 1.” The National Center for Biotechnology Information, Journal of the International Society of Sports Nutrition, 3 Dec. 2013, www.ncbi.nlm.nih.gov/pmc/articles/PMC3879660/figure/F1/.

This figure shows a visual distribution of the results of each study for hypertrophy along an overall mean using the base model.

Impact of protein timing on Hypertrophy by study-Basic Model
Schoenfeld, Brad, et al. “Figure 2.” The National Center for Biotechnology Information, Journal of the International Society of Sports Nutrition, 3 Dec. 2013, www.ncbi.nlm.nih.gov/pmc/articles/PMC3879660/figure/F2/.

This figure shows a visual distribution of the results of each study for hypertrophy along an overall mean using the full model. This model adjusts for protein intake.

Schoenfeld, Brad, et al. “Figure 3.” The National Center for Biotechnology Information, Journal of the International Society of Sports Nutrition, 3 Dec. 2013, www.ncbi.nlm.nih.gov/pmc/articles/PMC3879660/figure/F3/.

What does this mean?

If you just looked at the basic model, that did not control for some confounding factors, you would be lead to believe that protein timing had an effect on muscle growth. When the total amount of protein was accounted for, the advantage disappeared.

When the subjects underwent some of the studies, the controls and variable groups did not do a great job of matching the total amount of protein consumed. When more protein was consumed, more muscle was built.

There were some admitted weaknesses of the studies admitted by the authors:

  • Timing varied a lot in control studies. Some limited protein for several hours after training.
  • The majority of studies used untrained subjects who are known to respond different to training.
  • Not many studies had well trained participants.
  • Studies didn't match the total amount of protein people ate in controls to that of the other groups.
  • Some studies gave results in increases in CSA (cross sectional area of muscle), others used FFM (muscle, bone, connective tissue etc.) these results were both pooled together, though the authors don't think this affected results much.

What does this mean for you?

There's no guaranteed special advantages to slamming protein a shake right after your workout.

Upon further exploration of the interwebs, there was not enough data to give a definitive answer on whether it helped but, Brad Schoenfeld (one of the researchers) had this to say on facebook discussing the research:

"There might be small differences that are not detectable in research and these differences might be meaningful to someone who is trying to maximize hypertrophy. The topic still needs quite a lot more research, but I feel our study shows that for the majority of the population you don't need to worry about scarfing down a protein shake as soon as your workout is done."

Ultimately, as long as you get enough protein somewhere around 1-3 hours before and or after exercise as well as throughout the day, you should be good to go.

References:

  1. Schoenfeld, Brad, et al. “The Effect of Protein Timing on Muscle Strength and Hypertrophy: a Meta-Analysis.” Journal of the International Society of Sports Nutrition, vol. 10, no. 1, 2013, p. 53., doi:10.1186/1550-2783-10-53.
  2. Lemon, P. W., et al. “Protein Requirements and Muscle Mass/Strength Changes during Intensive Training in Novice Bodybuilders.” Journal of Applied Physiology, vol. 73, no. 2, 1992, pp. 767–775., doi:10.1152/jappl.1992.73.2.767.
  3. Morris, Scott B., and Richard P. Deshon. “Combining Effect Size Estimates in Meta-Analysis with Repeated Measures and Independent-Groups Designs.”Psychological Methods, vol. 7, no. 1, 2002, pp. 105–125., doi:10.1037//1082-989x.7.1.105.

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