How Much Protein Do You Need for Muscle Growth?

Protein is hands-down the most researched macronutrient when muscle growth is the topic of interest. Most gym-goers and bodybuilders assume the more protein in their diet, the better. But how much do we really need for building muscle mass? Let’s take a look at the science behind protein intake.

The health and fitness industry has a tendency to divide topics into polar extremes, leaving a gaping hole in the middle ground. For example, many people view foods as being either “clean”or “dirty”, and there’s no in-between. It’s not surprising then that the topic of protein needs for muscle building would fall victim to this trend.

We’re not saying that “moderation” is always the best, but neither is an all-or-none approach. With this in mind, let’s take a deeper look at what makes sense in terms of protein needs for building muscle mass. The science may surprise you…

Based on recent research findings and clinical nutrition recommendations, it’s safe to say that 1.2 to 1.5 grams of protein per kilogram of bodyweight is a sufficient intake for healthy adults (though slightly more is advised for highly active individuals).1 Most bodybuilders advise eating upwards of 4 grams of protein per kilogram of bodyweight, which is rather astronomical for most gym-goers (assuming they’re not on performance-enhancing drugs).

For active adults who lift weights and exercise regularly (and want to build muscle) then a generous baseline of protein intake would be around 2.5 grams per kilogram of bodyweight. In the empirical system, this equates to roughly 1.15 grams of protein per pound of bodyweight. While that may not seem like a lot, eating 1.15 grams of protein/lb of bodyweight per day is more than enough for most gym-goers. The main thing to note is that you can certainly eat more, or less, protein, but not all of it will necessarily go towards new muscle growth (more on this to come).

A common question that people often ask is if it matter how quickly (or slowly) protein is digested and utilized? Does all digested protein go towards muscle protein synthesis? Now that we have a better understanding of protein digestion, it’s important to note that not all the amino acids and small peptides will go towards synthesizing new muscle tissue. In other words, eating 100g of protein at once won’t result in an even larger surge in MPS than a more modest quantity (particularly because there appears to be a “cap” to MPS at any given feeding).

Based on findings from research, 30+ grams of a leucine-rich protein source (such as most animal proteins and milk proteins) will suffice to elevate, and likely “cap” out, the MPS response to feeding for at least 3-4 hours (with a few exceptions that will be noted in just a bit).2,3

This isn’t to say that everyone should limit their protein intake to 30 grams at a time for optimal muscle growth. Larger individuals will obviously need more and vice versa. Moreover, protein that doesn’t go towards protein synthesis is still biologically useful for other processes.

However, consuming an exorbitant amount of protein at once (like 200+ grams) will likely result in a large portion of those amino acids being oxidized and sent to the liver for gluconeogenesis, converted to fat, and/or be excreted.

As many readers likely know, whey and casein are complete proteins and often referred to as “fast” and “slow” digesting proteins, respectively. This is largely due to the nature of casein to form a gel when it is digested, and the amino acids are slowly dispersed for upwards of six to eight hours. Whey protein, on the other hand, is rapidly absorbed – in as little as one hour – when ingested on its own. It’s important to note that complex carbohydrates and fatty acids tend to slow down the digestion process.

If we break down what it means for a protein source to be “best”, we are looking for a protein that maximizes muscle protein synthesis (MPS) in response to feeding and a protein that is well absorbed/digested. MPS is differentially stimulated in proportion to the EAA content (and particularly L-leucine) of each feeding.4 Thus, mixing various incomplete protein sources from various foods sources can still achieve the same effect as only consuming one complete protein source.

Moreover, research has demonstrated that mixing protein sources may be more effective than relying on one source repeatedly.5 For example, the abundant leucine content of whey paired with the delayed-release nature of casein can provide a sustained elevation of protein synthesis for several hours after ingestion, which would not occur with solely whey protein.

Therefore, it’s not really prudent to label a single protein source as being “the best” when many sources of protein are suitable. There’s no reason a vegetarian couldn’t build just as much muscle as a carnivore so long as sufficient EAAs (and overall grams of protein) are being consumed. Nevertheless, whey protein, the proclaimed “gold standard” of protein supplementation, is undoubtedly one of the best sources of EAAs (especially L-leucine).

As alluded to earlier, these suggestions are meant to be a starting point for active individuals. Various factors such as body mass, age, genetics, performance-enhancing drugs, etc… will alter your specific protein needs. Don’t be afraid to do some trial and error to find out what suits you best. As rules of thumb though, remember these tips
Consume roughly 1 to 1.25 grams of protein per pound of your body weight
Ideally, consume at least 30 grams or more of leucine-rich protein(s) at each meal
For muscle building, eat at least four to five protein-rich meals per day, spaced 3-4 hours apart

1. Deutz, N. E., Bauer, J. M., Barazzoni, R., Biolo, G., Boirie, Y., Bosy-Westphal, A., … & Singer, P. (2014). Protein intake and exercise for optimal muscle function with aging: recommendations from the ESPEN Expert Group. Clinical Nutrition, 33(6), 929-936.
2) Anthony, J. C., Anthony, T. G., Kimball, S. R., Vary, T. C., & Jefferson, L. S. (2000). Orally administered leucine stimulates protein synthesis in skeletal muscle of postabsorptive rats in association with increased eIF4F formation.The Journal of Nutrition, 130(2), 139-145.
3) Koopman, R., Verdijk, L., Manders, R. J., Gijsen, A. P., Gorselink, M., Pijpers, E. & van Loon, L. J. (2006). Co-ingestion of protein and leucine stimulates muscle protein synthesis rates to the same extent in young and elderly lean men. The American journal of clinical nutrition, 84(3), 623-632.
4) Norton LE, Wilson GJ, Layman DK, Moulton CJ, Garlick PJ. (2012) Leucine content of dietary proteins is a determinant of postprandial skeletal muscle protein synthesis in adult rats. Nutr Metab (Lond). 2012 Jul 20;9(1):67. doi: 10.1186/1743-7075-9-67. PubMed PMID: 22818257; PubMed Central PMCID: PMC3488566
5) Reidy, P. T., Walker, D. K., Dickinson, J. M., Gundermann, D. M., Drummond, M. J., Timmerman, K. L., & Rasmussen, B. B. (2013). Protein blend ingestion following resistance exercise promotes human muscle protein synthesis. The Journal of nutrition, 143(4), 410-416.

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