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How To Optimize Muscle Protein Synthesis Through Strength Training & Diet

Molly Knudsen, M.S., RDN
August 18, 2023
Molly Knudsen, M.S., RDN
Registered Dietitian Nutritionist
By Molly Knudsen, M.S., RDN
Registered Dietitian Nutritionist
Molly Knudsen, M.S., RDN is a Registered Dietician Nutritionist with a bachelor’s degree in nutrition from Texas Christian University and a master’s in nutrition interventions, communication, and behavior change from Tufts University. She lives in Newport Beach, California, and enjoys connecting people to the food they eat and how it influences health and wellbeing.
August 18, 2023
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Do you go to the gym (or run or go to fitness classes) regularly, yet you don't notice your muscles looking any more toned than before? Well, it's a tough break, but exercise doesn't automatically translate to muscle growth. 

And whether or not you gain muscle, lose it, or maintain what you currently have, depends on the rate of muscle protein synthesis—which is primarily regulated by resistance training and protein consumption.

Let's break down the basics of muscle protein synthesis so you can get the most out of your workouts and your meals. 

What is muscle protein synthesis? 

Muscle tissue is dynamic, and muscle proteins are being broken down and created (simultaneously) throughout the day. 

Muscle protein synthesis 1is the muscle creation side of this equation. During this process, the body incorporates amino acids (aka the building blocks of protein) into muscle tissue to produce new muscle proteins. These can be contractile proteins like actin and myosin, the proteins that regulate those contractions, or structural proteins that aid muscle stability. 

Having adequate muscle and lean tissue is beneficial for cognition, metabolic health2, and inflammation levels3. It also helps protect you from bone fractures4 that become more common with age.

So is muscle protein synthesis the same as muscle growth?

Not quite. For muscles to grow, the rate of muscle protein synthesis has to outpace that of muscle protein breakdown. 

If it doesn't, then muscle size will either stay the same or shrink (and we definitely don't want that to happen).

What promotes muscle protein synthesis? 

Two main scenarios that drive muscle protein synthesis 5for adults: strength training and protein intake. 

And this isn't a one-or-the-other situation. Both are needed to truly maximize muscle synthesis and then, hopefully, growth. Here's your action plan for revving up muscle protein synthesis:


 Prioritize & monitor your protein intake 

Dietary protein provides the body with the amino acids needed to build proteins. There are 20 amino acids that make up all the proteins in the human body. The body can produce some amino acids internally, but nine amino acids are essential and have to be consumed by the diet. 

So you have to get enough protein in general, and enough of the right amino acids for muscle protein synthesis. 

What kind of protein is best? 

Both animal proteins (like meat, fish, poultry, dairy, eggs, etc.) and plant proteins (like tofu, lentils, legumes, nuts, and seeds) provide amino acids.

Animal proteins are deemed complete proteins because they contain all nine essential amino acids. Some plant foods (like quinoa, soy, and buckwheat) are also complete proteins, but most aren't. 

You can still technically get the protein you need for muscle health if you follow a vegan or vegetarian diet. But you need to be very diligent about eating enough (and a variety of) plant foods. 

Protein powders also deliver a concentrated source of amino acids. Whey protein, in particular, is linked to protein metabolism—especially after strenuous exercise6—due to the fact that it's high in the essential amino acid leucine. Research shows that leucine helps initiate and regulate7 muscle-building processes, and it takes about 2.5 grams of leucine8 to stimulate muscle protein synthesis. Most plant proteins do not meet this important threshold.

How much protein do you need to eat to promote muscle protein synthesis? 

The exact amount of protein you need is individualized and depends on your age, sex, activity level, muscle mass, and overall health. 

The bare minimum protein recommendation for healthy adults is 0.8 gram per kilogram body weight a day (for someone weighing 150 pounds, that's about 55 grams). 

But to really stimulate muscle protein synthesis, researchers recommend aiming much higher9 for about 1.6 to up to 2.2 grams per kilogram body weight daily. So that same 150-pound person would need about 109 to 150 grams of protein a day. 

"What's approachable is to aim for 20 to 30 grams of protein each meal," says registered dietitian and health coach Jessica Cording, M.S, R.D., CDN, INHC. Then add in some high-protein snacks, and you're well on your way to reaching your protein goals.

When should you eat your protein to optimize muscle gains? 

When you consume protein also matters. 

Although most people eat the bulk of their daily protein intake at dinner, amino acid researcher Don Layman, Ph.D., previously told mindbodygreen, "The first meal of the day after a nighttime fasting period is the most important for muscle protein synthesis." 

So, a high-protein breakfast is important. But protein should be a component of every meal (and snack) throughout the day to keep a steady supply of amino acids available to the muscles, especially in the hours after a workout. 


Protein from foods supply your body with the amino acids it needs to build muscles. Animal proteins tend to contain a more beneficial mix of amino acids than plants. Most people should aim for at least 100 grams of protein a day. 

Step up your strength training

While there are still numerous benefits to cardio exercise 10(like improving heart health and blood pressure), "doing cardio without paying mind to strength training exercises isn't adequate enough to build muscle," says Cording.

Strength or resistance training11 means that you're working your muscles against a force. This resistance is created from body weight, weight machines, or resistance bands. It can also be carrying laundry or children up the stairs. 

This resistance damages the muscle, creating tiny tears in the tissue. And this is actually a good thing. This damage signals repair processes12 to grow the muscle back stronger. 

"It's important to keep in mind that this growth can only happen when sufficient tension is put on your muscles," registered dietitian and certified personal trainer Brianna Frutchey, R.D., CPT, previously told mindbodygreen. 

"If we are continuously lifting the same amount of weight at the same amount of reps each week, muscle growth will plateau," she notes. 

How much strength training should you do? 

The American College of Sports Medicine 11recommends including at least two days a week of strength training to work all major muscle groups (including your glutes, hamstrings, back, shoulders, abdomen, etc.).

But the duration of the session, the number of reps, and the degree of resistance will vary by person. "It's important to be intentional with strength training at a level that's appropriate for you," emphasizes Cording.

Not sure where to start? Check out our comprehensive guide to strength training here


Some resistance training is needed for muscle protein synthesis. Aim to train at least two days a week at a level that's appropriate for you.


What is the best meal timing for muscle protein synthesis?

Protein intake should be distributed throughout the day. Most people eat the bulk of their protein during the evening meal, but a general rule of thumb is to get 20 to 30 grams of protein at three meals a day (sometimes with snacks containing 10 to 15 grams). 

What stimulates muscle protein synthesis?

Dietary protein intake and resistance training stimulate muscle protein synthesis. At a molecular level, this process is regulated by the mTORC1 pathway. And stress inhibits this pathway and can be detrimental to muscle protein synthesis. 

The takeaway

Muscle protein synthesis is an ongoing process in the body. And stimulating this process is vital to maintain the muscle mass that you currently have and to grow it. The best way to optimize this internal process is to make sure you prioritize protein intake at each meal (totaling around 100 grams a day) and incorporate strength training at a challenging—yet appropriate—level for you.