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What Is Protein Synthesis? (Everything You Need To Know)

Donald Christman
Published by Donald Christman
Last updated: April 23, 2023

After being in the world of fitness for over two decades, I understood how muscles grow intuitively, but I really wanted to gain a deeper and more nuanced understanding of the actual process of muscle protein synthesis.

My curiosity got me going through many studies on this matter, providing me with a better grip on the underlying science. But, naturally, to be pragmatic as well, I also found out how it applies to my workout routine.

To spare you the reading marathon, here is the summary of my findings that should hopefully enable you to work out both hard and smart.

Quick Summary

  • Protein synthesis is the process in which the body produces new proteins to repair damaged body tissues.
  • Meals that are rich in protein, and low in carbohydrates promptly support protein synthesis.
  • The protein synthesis process takes roughly 72 hours after a workout occurs.

What Is the Process of Protein Synthesis?

Woman showing her back muscles

Protein synthesis is the process through which our body produces new proteins in order to repair old damaged tissue and enable all body processes dependent on this vital molecule.

We are specifically interested in muscle protein synthesis (MPS) because it’s crucial to the maintenance and growth of muscle tissue.

Proteins are complex organic molecules that have building units called amino acids.

Our stomach uses stomach acid and certain enzymes to break down the food we eat into small bits that our intestines can absorb [1].

The amino acids that we’ve gotten this way from protein sources like meat then get into our bloodstream and disperse throughout the body, where they are used to “synthesize” or, in other words, make new proteins used to build new muscle tissue.

We won’t get into the actual step-by-step biological process of protein synthesis because it includes minute particles of our cells like DNA and ribosomes, as well as complex processes like transcription and translation [2].

An in-depth understanding of this complex topic requires certain prior knowledge and considerable time and effort, so I won’t burden you with that.

What we’re going to do is focus on the more practical aspects of this, which can be applied in your everyday life.

What Type of Diet Supports Protein Synthesis?

A type of diet rich in proteins and low in carbohydrates supports protein synthesis.

Eating 20g of protein gives a linearly proportional increase in muscle protein synthesis rate. This simply means that eating 20g of protein will double the MPS rate as opposed to eating 10g [3].

If you take 20 to 40 grams of protein, an increase in muscle protein synthesis will also occur. However, it will be much less noticeable — 40 g will only give you an MPS rate about 10% higher than 20 g will [4].

"Is it 10g of protein more or 10g of protein less, who cares, just get started"

- Kai Greene, American Personal Trainer

What Foods Stimulates Muscle Growth?

Top view of meats and dairy foods

Easily digestible food, rich in all essential amino acids, stimulates muscle growth.

It’s important that you get the complete amino acid profile from your food, which can be attained primarily from animal sources like lean meats, eggs, and dairy.

Though animal-based proteins have higher amino acid concentrations, some suggest that vegans might satisfy their needs by simply consuming larger quantities of plant-based proteins [5].

Whey is one of the most widespread protein sources,  known for high levels of one invaluable amino acid — leucine (which I’ll cover next). It’s also very easy to digest unless you are sensitive to milk proteins or lactose.

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The Importance of Leucine

There are nine essential amino acids that you must obtain through your diet in order to make protein synthesis possible [6].

Leucine is one of those amino acids, and it’s especially important for MPS because increased concentrations of this amino acid were shown to correlate with greater MPS rates [7].

Furthermore, when added to low protein doses, relatively small amounts of leucine produced the same effect as large protein doses [8].

How Does Exercise Affect Protein Synthesis?

Black curvy woman doing exercise in her room

Exercise affects protein synthesis by causing microscopic damage to the activated muscles, which acts as a signal for protein synthesis to unfold [3].

Essentially, when you make small tears in your muscle tissue due to exertion, muscle protein synthesis occurs in those places and practically “fills the gap”, and your muscle mass grows by the exact amount of that gap.

If you’re only starting to work out, MPS primed by exercise will be geared towards repairing broken muscle tissue.

You probably don’t have to max out in each set.

Especially if maxing out makes you unable to do the same number of reps throughout your following sets.

Repeats to failure have an accumulative effect, undermining sustained efforts in the long run [9]. Not nearing failure, on the other hand, is proven to provide suboptimal MPS [10].

Studies show that, at least when starting to train, repeating near failure is most beneficial for muscle protein synthesis [11]. Once you grow in strength, it might be best to get as close to failure as you can.

Other Influences on Muscle Protein Synthesis

Top view of food collage, woman pinching her arm muscles

Carbohydrates: Simultaneous ingestion of proteins and carbs was shown to delay the digestion of protein [12]. However, no effects on MPS were observed [13].

Fats: Not yet thoroughly investigated, the influence of fats on MPS is believed to be negligible.

Insulin: Unlike with muscle protein breakdown, natural levels of insulin exhibit no influence on muscle protein synthesis [14]. On the other hand, abnormal doses of insulin could stimulate muscle growth, and some bodybuilders make use of this application.

Meal Distribution: To optimize muscle growth, you should space out your meals throughout the day. Taking evened-out servings of food rich in protein is more conducive to high MPS rates than having most of your daily protein for dinner [15].

Having said that, it’s equally important not to overdo it. Taking 20g every 3 hours was proven to stimulate MPS better than having smaller doses more often or taking larger doses less often [16].

Eating Before Sleep: An evenly distributed protein intake is our clear objective when we're looking to muscle up. It’s therefore advisable to eat before bed. Our last meal for the day is beneficial to overnight MPS and leads to increased strength and muscle mass in long-term training programs [17].


Why Is Protein Synthesis Important?

Protein synthesis is important because it maintains the growth of all living organisms. It’s also at the very core of muscle growth.

How Long After a Workout Does Protein Synthesis Last?

Protein synthesis lasts up to 72 hours after a workout. Studies suggest that the body reaches peak muscle protein synthesis within 24 hours after training [18].

Do Carbs Increase Protein Synthesis?

Carbs don’t increase protein synthesis, but they do slow down the breakdown of bodily proteins, which indirectly helps you in growing muscle mass.

Should I Devote Each Day to One Muscle Group?

You shouldn’t devote each day to one muscle group. It is best to train the same muscle group twice a week. You experience higher rates of MPS for up to 3 days after the workout, with its maximum around the 24-hour mark. So, waiting for a full week before devoting your training to that one muscle group yet again is a bad idea.

What Does Protein Synthesis Mean For You?

As we’ve learned, protein synthesis is an essential process for all life, and muscle protein synthesis is just a small part of it.

A lot still remains to be understood about MPS, but if your main focus is how to support this process for muscle growth, there are definitely certain habits you can adopt to speed things up.

Mainly, you should eat a protein-rich diet that is not lacking in any essential amino acid, especially leucine, and exercise as close to failure as you can.

And on those busy days when preparing a good meal is simply not an option, try and stay on the right path by quickly making a shake with some of the best protein powders for muscle gain available on the market today.


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