Building muscle requires a steady supply of amino acids from protein. You want to get bigger and stronger? You have to eat enough protein.
However, the effect of protein timing remains a matter of debate. One popular theory is the anabolic window, a short time frame after training, during which protein intake is most influential for muscle gains.
No one wants their effort in the gym to be wasted. But does the timing of when you eat protein really matter? Let’s take a closer look at:
- How the body uses protein to build muscle
- The anabolic window theory
- The science behind protein timing
- Strategies to optimize protein intake for muscle growth
Resistance Training and Protein Needs
Resistance training is the process by which you challenge a muscle beyond its current capacity to stimulate an increase in strength and size.
The body is highly adaptable. Consistent weight lifting leads the body to adapt to new demands.
When you lift heavy loads, you induce controlled, microscopic tears in muscle fibers. The damage signals the body to initiate a repair process. However, instead of repairing the muscle back to its baseline, the process builds stronger muscle fibers to better prepare it for future loads.
Amino acids are the building blocks for muscle growth. To build more muscle, you need enough amino acids to not only meet your baseline protein requirements, but also a little extra to allow for added growth.
The process of muscle repair and growth begins immediately after you exercise. Which begs the question: how soon do you need to consume protein to meet the demand for amino acids?
The Anabolic Window Theory
The anabolic window is known in weightlifting circles as the period of time after exercise during which the body is most active in building muscle.
Anabolic refers to the process of anabolism, which is when smaller molecules grow into larger, more complex molecules, such as the process of building proteins from amino acids.
The theory claims that the window for maximum anabolism, or muscle growth, is a short time frame, within 30-60 minutes after a workout. During that time, the theory suggests that muscles are primed for an infusion of amino acids, and failure to consume enough protein during this window will decrease your gains.
This sounds reasonable, which is why the theory has been part of weightlifting programs for decades.
However, just because a theory sounds plausible does not guarantee its accuracy. The body is often more complex and more adaptable than it first appears.
The Science of Protein Timing
Research into the theory of an anabolic window has produced mixed results.
A recent meta-analysis examined the results of 65 randomized controlled trials involving 2,900 participants. [1] Results showed a positive impact of protein supplementation on lean body mass; however, the timing of protein intake had no beneficial effect.
Conversely, a separate meta-analysis found that protein supplementation after exercise and in the evening promoted greater gains in muscle mass and strength compared to a placebo. [2] Note that it was not only post-exercise supplementation that was beneficial, but also supplementation at night.
A 2013 meta-analysis concluded that total protein intake, regardless of timing, is the most significant predictor of muscle mass and strength gains achieved through resistance training. [3] In their review of the literature, the study authors found that many studies that claimed a positive benefit to protein supplementation within 1 hour of exercise had not controlled for total protein intake between the intervention and control groups.
Overall, the research is highly variable with many confounding factors.
- Inconsistent timing of protein
- Lack of control for total protein intake
- Trained vs. untrained participants
- Training routine and intensity
- Training in a fasted vs. fed state
- Small study size of a short duration
There is ample evidence that the so-called anabolic window is much wider than the traditionally touted 60 minutes. [4] And what the science tells us with a high degree of certainty is that getting enough total protein is the real essential key for muscle growth and recovery. [5]
Optimize Your Protein Intake
Until more consistent research emerges, it’s reasonable to prioritize getting enough protein and worry less about the exact timing.
If you’re eating a normal meal rhythm with evenly spaced breakfast, lunch, and dinner plus maybe a snack, you’re likely already consuming protein an hour or two before a workout and an hour or two after.
There’s nothing wrong with consuming a high-protein snack immediately after a workout, but if that doesn’t work for you, don’t stress. Despite what the gym bros may say, you’ve got more than 60 minutes to provide your muscles the protein they need.
Step 1: Eat enough protein
- Research shows 1.6 g/kg per day is a good baseline for building muscle. [6]
- Depending on your goal, you may choose even higher intake. Above 1.6 g/kg, you may still see benefits; however, the higher you go, the smaller the benefits become. [6] For the average weight lifter, those extra increments are likely unnecessary. If you’re a bodybuilder, those small gains may be more meaningful.
Step 2: Spread your protein intake out over the day
- Research on the concept of an “optimal distribution” of protein is mixed, and obtaining adequate amounts of protein remains the most crucial factor for muscle growth. [7]
- That being said, spreading your protein intake out over three balanced meals and perhaps a snack is the most practical way to ensure you get enough protein for most people.
- Distributing your protein throughout the day will also help ensure there are sufficient amino acids available in the hours before and after your workout.
Final Word
Total protein intake is the primary factor for muscle growth and recovery with resistance training.
Research suggests the optimal window for protein intake after a workout is likely longer than previously believed. Consuming a high protein snack or protein shake after a workout is great, but not essential if you otherwise get enough protein throughout the day.
Your specific goals will determine the optimal protein intake, distribution, and timing that works for you.
Need an easy way to hit your protein targets? Try Build, our delicious 100% whey protein isolate powder.
References:
1. Wirth, Janine et al. “The Role of Protein Intake and its Timing on Body Composition and Muscle Function in Healthy Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.” The Journal of nutrition vol. 150,6 (2020): 1443-1460. doi:10.1093/jn/nxaa049
2. Zhou, Huan-Huan et al. “Effects of Timing and Types of Protein Supplementation on Improving Muscle Mass, Strength, and Physical Performance in Adults Undergoing Resistance Training: A Network Meta-Analysis.” International journal of sport nutrition and exercise metabolism vol. 34,1 54-64. 1 Dec. 2023, doi:10.1123/ijsnem.2023-0118
3. Schoenfeld, Brad Jon et al. “The effect of protein timing on muscle strength and hypertrophy: a meta-analysis.” Journal of the International Society of Sports Nutrition vol. 10,1 53. 3 Dec. 2013, doi:10.1186/1550-2783-10-53
4. Aragon, Alan Albert, and Brad Jon Schoenfeld. “Nutrient timing revisited: is there a post-exercise anabolic window?.” Journal of the International Society of Sports Nutrition vol. 10,1 5. 29 Jan. 2013, doi:10.1186/1550-2783-10-5
5. Stokes, Tanner et al. “Recent Perspectives Regarding the Role of Dietary Protein for the Promotion of Muscle Hypertrophy with Resistance Exercise Training.” Nutrients vol. 10,2 180. 7 Feb. 2018, doi:10.3390/nu10020180
6. Tagawa, Ryoichi et al. “Dose-response relationship between protein intake and muscle mass increase: a systematic review and meta-analysis of randomized controlled trials.” Nutrition reviews, vol. 79,1 66–75. 4 Nov. 2020, doi:10.1093/nutrit/nuaa104
7. Hudson, Joshua L et al. “Protein Distribution and Muscle-Related Outcomes: Does the Evidence Support the Concept?.” Nutrients vol. 12,5 1441. 16 May. 2020, doi:10.3390/nu12051441
