If you’ve got a goal to build muscle, you need to be eating enough protein.

There is some debate about how much is necessary for the growth of maximal new muscle tissue. Some people say it’s 1g per lb of your bodyweight – but this feels too simplistic. Some people firmly believe that more is better, and will even eat 2g or more per lb of their bodyweight.

Others argue that even 1g per lb is overkill and you only need 1.6g per kilogram (which is about 0.73g per lb). Others believe that using your total bodyweight is incorrect and it’s the amount of lean or fat-free mass that is important, arguing that 0.8-1g of protein per lb of your fat free mass is the optimal amount.

There are a lot of different opinions. But what is the definitive answer? What does the science say? What happens when you put people in controlled environments, put them on well planned resistance training programs, with progressive overload, good sleep, and feed them different amounts of protein?

And what about different types of protein? Is the protein in eggs, the same as the protein in chicken? Are plant based sources of protein just as good?

These are the questions that this post will attempt to answer.

What is Protein?

Protein is one of three (four, if you include alcohol) macronutrients that can be found in food.

The other two are carbohydrates and fat.

Side note – want to know how much of each macronutrient you should consume for a muscle building or fat loss goal? Try my macro calculator.

Whilst all macronutrients can be used for energy, the body most easily uses carbohydrates and will burn these by default if they’re present.

Fat can also be used for energy, but it plays other important roles, such as vitamin absorption (vitamins A, D, E and K are fat-soluble, meaning they can only be absorbed in fat) and hormone regulation. Fat also contains essential fatty acids (omega 3 and omega 6) and these need to be present in your diet for optimal health.

Protein is not just used for creating muscle tissue. The word protein comes from the Greek word proteos meaning “primary”. It’s not a coincidence. Protein is very important and you need to make sure you’re getting enough of it in your diet. If you’ve got a goal to build muscle, then you’ll need more of it than other people.

As well as muscle tissue, protein also makes up skin, nails, hair, hormones, enzymes and cells (including red and white blood cells). We are totally made up of protein! Your body NEEDS protein, and if you don’t get enough of it, it will see what protein it can take from your protein stores – your muscles.

Amino acids

We can’t talk about protein, especially in a muscle building context, without talking about amino acids.

If protein is the building blocks of your body, amino acids are the building blocks of proteins.

Over 500 amino acids have been observed in nature, but only 20 of these are found in the human body.

They are:

• Alanine
• Arginine
• Asparagine
• Aspartate
• Cysteine
• Glutamine
• Glutamate
• Glycine
• Histidine
• Isoleucine
• Leucine
• Lysine
• Methionine
• Phenylalanine
• Proline
• Serine
• Threonine
• Tryptophan
• Tyrosine
• Valine

Different amino acids serve different functions such as tissue growth, energy production, immune function, and nutrient absorption.

Of the 20 amino acids found in the human body, 9 are “essential amino acids”, meaning that the body cannot produce them. You must get them through your diet.

These are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

Why am I going into this much detail about amino acids? Well, because it matters for building muscle. If you want to build muscle optimally, you’ve got to be getting these essential amino acids, in particular leucine.

Not all protein sources contain these essential amino acids in high concentrations. Plant based sources of protein generally don’t contain high levels of all nine essential amino acids and are termed “incomplete proteins”. If you are a vegetarian or vegan, you will have to plan your diet more carefully to ensure you’re getting enough of all the essential amino acids. If you’re on a plant based diet and you don’t plan out where you’re getting your amino acids from, you can easily miss some of them. This is a problem if you want an optimal muscle protein response to your diet.

Animal proteins, on the other hand, are complete proteins. They contain all nine essential amino acids in high quantities. 100g of protein from beef is not the same as 100g of protein from beans, which will lack sufficient quantities of methionine and tryptophan.

Generally, animal foods will contain more of ALL the essential amino acids than a plant based comparison. Even if that plant based alternative does have a particular amino acid present, it will almost always not have as much of it as an animal protein source.

This matters when it comes to leucine – because of the role played by this specific amino acid in muscle building, and something called “the leucine threshold”.

Muscle Protein Balance

All throughout the day and night, your body is in either a positive or a negative protein balance. It’s either breaking muscle down into amino acids, or using amino acids supplied in the diet to rebuild muscle. Imagine it like a brick wall, and all the time bricks are either being taken out or put in.

When you eat, you usually provide at least some amount of protein, and your body goes into a positive protein balance for a few hours. When this happens, you have muscle protein synthesis. In other words, your body can repair muscles and create new muscle tissue at this time.

When there’s no protein on hand, your body still needs amino acids so it looks to where else it can get them: your muscle stores. This is when you’re in a negative protein balance and muscle protein breakdown is occurring.

Most people never really need to worry about this, and over the course of the day these processes are mainly balanced out – resulting in a net retention of muscle mass.

When you’re resistance training, you are stressing and damaging muscle fibres and therefore you need more protein in your diet so they can be repaired.

The Leucine Threshold

There is one essential amino acid which has a very important function for building muscle: leucine.

Leucine is critical for muscle protein synthesis and muscle repair. It is the amino acid that acts as a signal to the body to go and build muscle. When foods containing leucine are ingested in sufficient amounts, muscle protein synthesis begins.

The more leucine you have on hand, the better the muscle building response will be – up to a point.

There is a certain amount of leucine that will result in maximal stimulation of muscle protein synthesis, and beyond this amount the response does not increase. This is known as the “leucine threshold”. This amount is about 2.5g of leucine per meal. After the meal, muscle protein synthesis remains elevated for 3-4 hours. Ingesting more protein during this time doesn’t start it again or extend the time MPS stays elevated.

Depending on your protein source, the amount of protein you need to eat to get 2.5g of leucine will be different. That’s why 30g of protein from beef is better than 30g of protein from quinoa. Yes quinoa is technically a “complete protein” because it does contain leucine and the other essential amino acids. But to get the BEST muscle building response 30g of protein from quinoa isn’t going to cut it. You’d need 42g of protein from quinoa to get this amount of leucine. Added to this, quinoa is pretty calorie dense when you want to get significant quantities of protein from it. 42g of protein from quinoa requires A LOT of quinoa (over 1,000 calories worth).

Beef, on the other hand, has leucine in higher concentrations so you only need 29g of protein from beef to hit 2.5g of leucine, and that comes out to about 180 calories worth of beef. This is much more efficient and leaves plenty of room in your daily calorie intake for other foods. Who wants to be full of quinoa all day?

Simply aiming for a total protein target per day isn’t the best strategy

One of the common pieces of advice given to beginners who are just starting to track their macros is that when they eat does not matter, and they should just focus on hitting their overall numbers for the day. This leads to a belief that the timing of nutrients doesn’t make a difference.

In reality, it DOES matter. This advice is probably given to beginners because we are trying not to overwhelm them with too much complexity, and they will still see major benefits from hitting the overall target amount, even if not spread out optimally.

You can see from the leucine discussion that splitting your protein intake into several meals containing at least 2.5g of leucine, and spreading them out by 4 hours, is a better approach than simply aiming to hit your overall goal with any timing of protein, and no thought to leucine.

Research has found that splitting your protein intake evenly across the day is significantly better for hypertrophy. This study found that consumption of a moderate amount of protein at each meal stimulated 24 hour MPS more effectively than skewing protein intake toward the evening meal. The results of the study were that the evenly distributed protein group saw 25% higher muscle protein synthesis than the group taking in the same total amount of protein, but skewed towards their evening meal.

Many studies agree that 1.6g of protein per kg of bodyweight is the recommended amount for optimal hypertrophy. This study goes further and suggests that target is reached by combining 4 meals of at least 0.4g per kg.

I’m in agreement. There’s various reasons why just aiming for a total protein target with no thought to distribution isn’t as good as planning out how you’re going to hit your protein target.

For example:

Imagine a person with a 120g per day protein target.

Scenario 1:

• 3 meals + 1 snack.
• 35g protein from eggs at 7am.
• 30g protein from beef at 12pm.
• 30g protein from chicken at 5pm.
• 25g protein from a whey protein shake before bed at 10pm.

Scenario 2:

• 3 meals.
• 30g protein from quinoa at 10am.
• 20g protein from cod at 12pm.
• 70g protein from beef at 7pm.

Both examples involve a person hitting their protein goal of 120g of protein. However, the first scenario is far more optimal than the second, for many reasons.

Why you’ve got to plan your intake of protein throughout the day

Firstly, If we look at the amount of leucine being ingested with each meal, each of the meals in the first scenario hits the leucine threshold. Eggs, for example, are about 8% leucine. 35g of protein from eggs therefore provides 2.8g of leucine, above the 2.5g threshold. This is the case for all of the meals and snacks in scenario 2, including the 25g of whey before bed (whey is 10% leucine). This means that each of these meals will maximally stimulate muscle protein synthesis.

All of the meals and snacks are at least 4 hours apart, meaning muscle protein synthesis will have returned to baseline each time a new portion of protein is ingested. This is a very efficient way of spacing out protein intake, as it means you allow for the maximum effect from each dose before introducing the next dose. This approach allows you to get the maximum benefit from each dose and results in MPS being elevated for as long as possible.

If you look at scenario 2, not all of the meals provide enough leucine to maximally stimulate MPS. Quinoa is 6% leucine, so 30g of protein from quinoa only provides 1.8g of leucine. This means that this meal will provide a suboptimal stimulus for muscle protein synthesis. Quinoa is also not a very protein dense food, meaning you have to eat a lot of it to get a substantial serving of protein.

So to get 30g of protein, you need to eat 700g of quinoa (cooked weight). This is 987 calories worth (as it comes with 19g of fat and 159 grams of carbs)! On this note, plant sources of protein are all like this to varying degrees. If you’re looking to consume 30 grams of protein for less than 200 calories, then it has to be an animal source of protein. There are no plant sources of protein that can compare from a protein density or “calories per gram of protein” point of view.

Don’t have your protein doses too close together

Another thing worth mentioning from scenario 2 above is that the second meal does not provide enough protein to reach the leucine threshold. 20g of protein from cod will only provide about 1.6g of leucine – some way short of the 2.5g threshold. These meals are also spaced only 2 hours apart. It is very likely that muscle protein synthesis will still be elevated from the meal at 10am. Adding more protein at this time does not further elevate muscle protein synthesis. You would be better off waiting another 2 hours to eat again.

More protein doesn’t mean a bigger stimulus (past a certain point)

Looking at the final meal in scenario 2, 70g of protein from beef is ingested, but this is much more than is needed. It’s over double the amount of beef needed to provide 2.5g of leucine. That extra leucine is wasted, as it will further increase the MPS stimulus. A better approach would be to split this amount of beef into 2 meals spaced at least 4 hours apart.

To add another layer of complexity, you also need to plan your protein intake around your training sessions. You need to make sure you’re not training on a full stomach. You also want to make sure that at least one of these doses containing 2.5g leucine comes AFTER your resistance training sessions. You don’t have to get it in within 20 minutes, or anything like that. Within a couple of hours is fine. You just don’t want to be training and then not eating again for a significant period of time, for example if you train before bed without a pre-sleep serving of protein.

The bottom line

If you’ve got a goal to gain muscle, you should have a high protein intake.

A lot of recommendations are not based on science, such as the typical recommendation to eat “1g per lb of your bodyweight”. This is likely used as a recommendation because of its ease and because it will result in a recommendation that is more than enough.

Most scientific studies agree that there’s no benefit for hypertrophy to consuming more than 1.6g per kg of bodyweight.

If you want to optimise your results, you should focus on animal sources of protein, as these contain all essential amino acids in high concentrations. Leucine is the essential amino acid that’s of particular importance for muscle protein synthesis. 2.5g of leucine is the dose that’s needed to maximally stimulate MPS.

Certain plant sources of protein don’t contain enough leucine to fully stimulate muscle protein synthesis unless the serving is particularly large (which might be impractical).

Consuming more than 2.5g of leucine at once doesn’t further boost MPS. Once MPS has been stimulated it remains elevated for about 4 hours. It’s therefore wise to distribute your protein intake with several doses containing 2.5g leucine, spread 4 hours apart. This will result in stimulating MPS multiple times, whereas two doses closer together may result in a missed opportunity to spike MPS.