How Much Protein Do We Need to Maximize Muscle Growth?

The form, dosage, and spacing of protein intake for optimal muscle protein synthesis.

Protein intake is a confusing aspect of nutrition. I have seen so many different recommendations and conflicting studies about how much protein we should consume, how much we can absorb, and how frequently we should consume it.

When I was doing my BSc, we learned that our body can only absorb 14 g of protein in a single sitting, and therefore anything above this was a waste. This suggested that we should spread our protein intake out across the day in small doses.

But the other day I was reading research suggesting that we need to consume at least 30 g of protein in each meal if we want to stimulate muscle protein synthesis, which is the goal for a lot of us athletes.

So what do we do? Do we eat small doses regularly or big doses only a few times a day?

In this article, I disseminate the science and get to the hard facts about protein consumption.

What is protein?

Protein is the building block of our bodies — our muscles, molecules, enzymes, hemoglobin, bones, hair, and even nucleic acids such as our DNA are built from protein.

When we digest protein, it is broken down into its constituent parts — amino acids. These are transferred into our systemic circulation and are used for various functions; the body uses these constituents to make its own protein for building all the things mentioned above.

What is muscle protein synthesis?

Muscle protein synthesis (MPS) is the process of building muscle from protein. Thus, this is a very important process for anyone, but especially for athletes. This is how we recover and adapt to exercise.

MPS is minimally stimulated with resistance exercise at less than 20–40% of our one-rep maximum (1RM — the maximum load we can lift/move for one repetition) but is maximally stimulated at 70–90% of our 1RM. So, for example, if our 1RM squat is 80kg, then squatting 56–72kg is a great way to stimulate MPS. The rest of this article will focus on protein’s role in MPS.

What does the research say about protein intake?

It appears that it depends on many factors. Protein absorption and utilization are context-dependent, meaning in some cases we need less and in some situations we may need more, all to achieve the same result. And there may even be some variation in requirements between people.

Research has suggested that we only need 20–25 g of protein in order to stimulate MPS and that anything above this is oxidized and excreted. This is the dominant ideology in exercise nutrition research. However, the studies that suggest this often look at fast-absorbing protein which is not consumed with other macronutrients (macronutrients = fats, carbs, protein). So, likely something like a whey protein shake, which is a fast-absorbing form of protein that often doesn’t contain other macronutrients.

For example, one study showed that 20 g of whey protein every 3 hours 4 times a day maximized MPS compared to 8 servings of 10 g or 2 servings of 40 g, suggesting that 20 g is the sweet spot for fast-absorbing protein.

But these studies are conducted in isolation and therefore the results don’t transfer well to the real world beyond drinking protein shakes.

So what about when we eat protein as part of a meal?

The metabolism of protein is impacted by the composition of the source of protein, the other macronutrients the protein is consumed with, and even the exercise regime we follow, our age, and our muscle-mass. Eating protein with other macronutrients slows down the rate of absorption. Therefore, to understand protein utilization and absorption we must remember that the form of our protein and what we consume our protein with is going to affect how the body handles the protein. This will be discussed further below.

Net protein balance

We also need to consider net protein balance. That is, “the difference between skeletal muscle protein synthesis (MPS) and breakdown (MPB).” We want to keep a positive protein balance if we want to build muscle — where we are building more muscle than we are breaking down.

When a protein is fast-absorbing, such as the whey mentioned above, it can negatively impact our net protein balance. For example, whey protein has an absorption rate of 10 g/hour, so a 20 g serving of whey will be absorbed within 2 hours. However, an egg has an absorption rate of 3 g/hour, so two cooked eggs (about 12 g of protein) will take 4 hours to absorb, which leads to a positive net protein balance as the protein stays with us longer.

However, one caveat is that this fast-absorbing protein may be beneficial for anabolism (muscle building) in the short-term (under 4 hours) because of this rapid absorption, leading to greater stimulation of MPS. This suggests that it may be beneficial to consume fast-absorbing protein initially, and then to have some slower-absorbing protein to maintain protein balance throughout the day or night.

Can we eat too much protein?

There has long been debate over whether eating too much protein is bad for us. People have been saying too much protein will damage our organs, especially our kidneys, which process this excess. There have been no conclusive studies to prove this, and in fact, the increase in protein levels found in the urine after consuming a high dose of protein is the result of the body breaking down more of its old tissues to put this extra new protein to good use. Therefore, it’s a good thing.

We are also able to store amino acids for later use, meaning that any extra protein can be stored and is therefore not a waste.

Furthermore, protein absorption is the movement of amino acids from the digestive system into systemic circulation. In this regard, the absorption of protein is unlimited; we will digest all the protein we consume.

Protein immediately after strength training

As alluded to above, fast-absorbing protein seems to be beneficial for muscle building when consumed after training. While 20 g was identified as the usual sweet spot for fast-absorbing protein, it appears that consuming 40 g of fast-acting protein immediately after training leads to a greater anabolic reaction than consuming 20 g of protein.

But the real question is whether we need to immediately consume protein in the first place — the mystical “anabolic window” that we all try to tap into after our workout. The majority of sources I have read indicate that no, we don’t need to have protein right away — consuming protein immediately and not consuming protein immediately both lead to the same muscle gain in the long run.

“High-quality and short-term muscle biopsy studies report similar muscle anabolism after consuming an essential amino acid mix one, two or even three hours post-exercise…. This research clearly demonstrates that skeletal muscle remains responsive to protein ingestion during time periods outside the limits usually defined by the ‘anabolic window’. Indeed, it appears that this ‘anabolic window’ extends to 24 hours post-workout, or perhaps even longer.” — Oliver Witard, protein metabolism researcher and senior lecturer at the University of Stirling in Scotland.

The only case where it would be beneficial to immediately consume protein is if we have another bout of training/competition within 8 hours, in which case it would be advisable to consume some protein as quickly as possible to kickstart the recovery process.

Otherwise, as long as we’re reaching our total protein intake, we’re okay. While consuming protein immediately after training has short-term anabolic benefits, the long-term result is the same regardless of when we consume the protein — the topic of the next point.

Longer-term impact

“Acute anabolic responses are not necessarily associated with long-term muscular gains.” — Dr. Brad Schoenfield and Alan Aragon

What we’ve looked at so far is the impact of protein intake on immediate anabolic response. While it seems logical to assume that an acute anabolic response is the outcome we’re looking for, there is more to it than that. We need to look at the long-term results rather than the short term response of the body.

In terms of slow vs. fast-absorbing protein, one study found no difference after 8 weeks between supplementing with a slow-absorbing protein source compared to a fast-absorbing protein source.

In terms of protein spacing, one study found no difference between consuming a day’s worth of protein in one sitting and consuming the protein over the course of the day. Similarly, another study found no statistical difference between eating protein within a 4-hour window (time-restricted feeding or intermittent fasting) or spreading the protein consumption across the entire day.

Again, it appears that as long as we’re consuming enough protein, the form and spacing of it doesn’t matter so much.

Leucine levels

“It’s important to aim for a minimum serving about 30 g of protein…. because when we eat 30 g or more of protein, the concentration of a specific amino acid in our blood, called leucine, becomes high enough to cause our body to refresh and renew our lean tissue. The technical term for this is muscle protein synthesis — our body is rebuilding itself, and without activating this mechanism at least three times a day, we are missing out on all sorts of metabolic benefits and risk losing about 5% of our muscle tissue per decade.” — Jonathan Bailor, author of The Calorie Myth

It was this quote that prompted my interest in protein intake. 30 g of protein is a lot, and this suggests that eating less than 30 g at each meal will prevent us from receiving any benefits at all toward MPS.

Recent studies are suggesting that it is indeed leucine (an amino acid), not total protein, that is the important factor when looking at the relationship between protein consumption and MPS. And as alluded to in the quote above, we need 30 g of protein in one sitting to achieve the required amount of leucine. (It appears that protein is between 5–10% leucine).

One study showed that consuming a leucine-enriched whey drink increases muscle mass longer term — over a 6-week intervention, participants showed increased muscle mass compared to those not consuming the extra leucine.

“Consumption of BCAA (30 to 35% leucine) before or during endurance exercise may prevent or decrease the net rate of protein degradation, may improve both mental and physical performance and may have a sparing effect on muscle glycogen degradation and depletion of muscle glycogen stores.” — Antti Mero

Therefore, to further maximize MPS we can ensure we consume at least 30 g of protein at each meal, or we can look to supplement with leucine specifically. You can purchase leucine supplements, or take branch-chain amino acids (BCAAs), or essential amino acids (EEAs) to get an extra dose of leucine.

Implementation

So where does all this research leave us?

I think that Dr. Brad Schoenfield and Alan Aragon concisely and practically sum up the current research on protein intake:

“Based on the current evidence, we conclude that to maximize anabolism one should consume protein at a target intake of 0.4 g/kg/meal across a minimum of four meals in order to reach a minimum of 1.6 g/kg/day.”

So for a 75kg person, this means 30 g of protein per meal, for a minimum of four meals.

So what does 30 g of protein look like?

• 1 cup of Greek yogurt with 28 g of almonds
• 120 g chicken breast
• 7 slices of thick bacon
• 5 eggs
• 120 g of ground beef
• ¾ a block of tofu
• 1 large cup of cottage cheese

However, I think it is advisable even for those weighing less than 75kg to aim to consume at least 30 g of protein 4 times a day, or at least to supplement with leucine. While the research is still new and relatively inconclusive, it does appear that there is an increased benefit to consuming over 3 g of leucine in terms of MPS. So to maximize our MPS, we can look to consume our 0.4g/kg/meal x 4 meals, which may end up being 0.5g/kg/meal if we weigh less than 75kg and want to ensure adequate leucine.

I tend to aim for 30 g of protein at each meal to ensure I have my bases covered. The little bit of extra protein won’t do any harm, and it’ll make sure that I am maximizing the benefits.

Protein consumption is a confusing topic, and the research varies so widely that it is hard to come to any definite conclusion. However, it appears that consuming at least 30 g of protein at each meal, for four meals a day is advisable if we want to maximize our muscle growth. Of course, this recommendation will be different for those not looking to increase muscle mass with a whole different set of research to review.

But it appears that more than anything, we just need to make sure we are eating enough protein daily. While the spacing, form, and dosage of protein have different acute effects, it appears that the one aspect underlying all long-term muscle gain is that we are eating enough protein (1.6g/kg daily).

“As long as you hit daily protein intake, you can build muscle.” — Dr. Brad Schoenfield

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