Protein for Strength Athletes and Bodybuilders

Key Points:

  • Protein is the most important nutrient for building muscle.
  • Protein is made up of amino acids. Out of these, you need to get enough of the 9 essential ones through your food.
  • The average person needs at least 0.8 grams of protein per kilogram of body weight and day. Preferably 1.2 grams per kilogram.
  • If you’re looking to build muscle, you should aim for at least 1.6 grams of protein per kilogram of body weight and day. If you want to be sure you get enough, you can aim for 2.2 grams per kilogram.
  • When on a weight-loss diet, the amount of protein you need to prevent muscle loss increases. It could be as high as 2.7 grams of protein per kilogram of body weight and day.
  • A daily protein intake as high as 3.3 grams per kilogram for up to a year has no negative effects.
  • Your total protein intake is the most important thing to consider, by far. Things like protein timing and protein distribution might offer some additional, but much smaller, benefits.

Protein! Without it, you won’t survive long. And if you get too little of it, you certainly won’t perform your best or build any muscle.

The word “protein” comes from the Greek word for primary. Athletes, bodybuilders, and strength athletes need enough protein to increase performance, muscle size, and strength. Strength training plus protein equals a stronger and more muscular you.

This article will tell you everything you need to know about how protein helps you build muscle and get stronger.

Basic Functions of Protein and Muscle Growth

You need protein to maintain and repair every little cell in your body. Also, you need protein to build muscle and get results from your efforts in the gym.

Dietary protein is used to create new tissue and to repair the breakdown of tissue. It is required to promote growth. If strength training is your passion, you’re probably thinking “muscle” when you hear growth. Without plenty of protein, you’re not getting what you want from your training sessions.

When you eat as many calories as your burn off, you neither build nor lose muscle mass over time. Unless you add strength training to that equation. When you lift weights, you tell your body to build bigger muscles and to get stronger. Strength training and protein together act as a team. Both build muscle on their own, but together, they really pack it on. Over time, your training and protein intake turn you into a stronger and more muscular version of your old self.1

Protein is made up of building blocks called amino acids. Out of the 20 amino acids used to make the proteins required for health, growth, and repair, 9 are essential. Essential means that your body can’t make these amino acids on its own. You have to provide them with the food you eat. The essential amino acids are the ones your body needs from you to build muscle. The others, the non-essential amino acids, it can make when the need arises.

Several studies show how this works. If you eat 10 grams of essential amino acids, you build as much new muscle as when you eat 10 grams of essential amino acids plus 10 grams of non-essential amino acids. The non-essential ones do not bring anything extra to the table.2 3

Amino acids play more roles than as building blocks for new tissue. When they appear in your blood after you eat or drink protein, they tell your body “Hey! It’s time to build some muscle!” Your body then reacts by starting the processes that eventually lead to muscle growth.4 The road to muscle growth is paved with amino acids, and you act as the handyman laying down the bricks when you eat protein.

You don’t have to eat protein together with fat or carbohydrates if you don’t want to. Protein on its own builds muscle just as well as if you eat a complete mixed meal.5 People used to think that you need carbs along with your protein, for example in a post-workout shake, mainly because of fears that the protein would go to waste otherwise. That is not the case. Feel free to add carbs to your shake for recovery purposes, but don’t expect any extra muscle-building effects by doing so.

Another reason carbohydrates used to be more or less mandatory in a protein shake is because of insulin. Carbs release insulin, and the more insulin, the better the muscle growth, right? So we thought. This has since been refuted. You need insulin for protein to build muscle, but the protein itself releases more than enough. Insulin per se does not stimulate muscle protein synthesis but allows the muscle to use amino acids from the protein. However, even fasting levels of insulin is enough.6

Insulin reduces muscle breakdown, but more isn’t better here either. You get this effect at quite low levels of insulin. The protein in itself is enough. Higher insulin levels do not reduce muscle breakdown any further.7 8

Protein Recommendations for the General Population

For many decades, scientists and doctors recommended the same amount of protein for everyone. The basic protein recommendations for the population at large was enough for athletes as well. Things have changed. Now, we know that you need more protein if you are physically active and exercise, and even more, if you want to build muscle.

The most important thing to keep in mind when planning your protein intake is the total amount. Everything else, from meal frequency to protein timing and protein distribution, pale in comparison. That doesn’t mean that those things are irrelevant, but they won’t make or break your results. Eating too little protein might.

Both European and US authorities recommend a daily protein intake of 0.8 to 0.83 grams of protein per kilogram of body mass. 9 10 Don’t expect spectacular gains from that amount of protein. It covers the basic protein needs for 98% of the population, but “basic needs” aren’t necessarily optimal for health and performance.

These amounts are the results of so-called nitrogen balance calculations. You measure if the intake of nitrogen is greater than the loss, and a positive nitrogen balance suggests growth. This method has been criticized heavily. Studies using another method called the indicator amino acid oxidation (IAAO) method show that actual requirements for the average person could be 50% higher than the current recommendations. That would mean around 1.2 grams of protein per kilogram of body mass per day instead of 0.8 grams.11 Quite the difference.

When you get older, you need more protein to build muscle, both your total amount and the protein you get from a single meal. We’ll get to the latter later on in the article, but as for the optimal daily protein requirement for health and physical function in seniors, it’s likely as high as 1.0 to 1.3 grams per kilogram of body mass and day.12

Protein Requirements for Athletes

When the experts set the current RDI (Recommended Daily Intake) values for protein, they didn’t factor strength training and building muscle into the equation. You, however, probably do. If you want your lifting to pay off properly, you need more protein than the average pencil-pusher.

When you lift weights regularly, you increase the amount of protein you need to build new muscle and to repair damaged muscle protein. If you run, bike, or engage in some other form of endurance training, you use more amino acids as energy. That means that you need to eat more protein to give your muscles what they need as well.

A review article from 2011 recommends that you consume 1.3–1.8 grams of protein per kilogram of body mass per day if your goal is to build muscle. If you’re trying to lose fat at the same time, you’d do well to increase that amount to a whopping 1.8–2.7 grams per kilogram of body mass per day. When you burn more calories than you eat, you risk losing some of your hard-earned muscle, too. Eating more protein helps you prevent this.13

Protein Requirements for Bodybuilders and Strength Athletes

Bodybuilders and strength athletes who want maximal gains might benefit from eating even more protein than the average athlete. A 2018 meta-analysis concluded that 1.62 grams of protein per kilogram of body mass per day do just that: max your gains. Eating more than that amount did no harm, but didn’t add any more muscle either.14

A recent study that looked at the protein requirements of young male bodybuilders found the limit at 1.7 grams per kilogram of body mass per day. Again, more than that didn’t do any harm, but the researchers found that the excess was just used as energy. There are more efficient and cheaper sources of energy than protein.15

You might still need more than 1.7 grams of protein per kilogram of body weight and day to build as much muscle as possible. Those are average numbers, and some people can use more than that for muscle-building purposes. In the studies we just mentioned, a few of the bodybuilders could make use of 2.2 grams per kilogram of bodyweight.

In other words, 1.6–1.7 grams of protein per kilogram of body mass and day is enough for the vast majority of bodybuilders and strength athletes. However, if you really want to be sure you give your muscles enough building blocks for maximal results, you could aim for 2.2 grams per kilogram. There is no harm in doing so.

You can use our protein calculator to estimate your daily protein need.

Protein Per Meal

Only a couple of studies investigate how much protein you can use from a single meal to build muscle. You can absorb and use all the protein you eat. Whether you use it to build new muscle is another thing entirely.

Two of these studies show that eating or drinking 20 grams of egg or whey protein is enough to max out muscle protein synthesis after a workout.16 17 If you increase that amount, you don’t build any more muscle. Instead, you use the excess as energy and to build other tissue than muscle, like organ and skin protein. Those 20 grams of protein are enough both after a training session and at rest.

However, in those two studies, the participants only trained a single muscle group. A later study found that if you train several muscle groups, like in a full-body workout, you need 40 grams of protein to build as much muscle as possible.18. Doubling the amount of protein does not double the amount of muscle you build after the workout, but rather around 20% more.

Drinking a protein shake after a workout is one thing, but what about regular food? In a 2009 study, 34 young and old men and women ate either 30 or 90 grams of protein in the form of lean beef. The researchers measured their muscle protein synthesis after the meal and found that 90 grams of protein didn’t stimulate it more than 30 grams.19

When you get older, not only do you need more protein overall, you also need more protein per meal. While young people need 40 grams of protein after a full-body workout to fully stimulate muscle protein synthesis, seniors need that much regardless of the workout. In other words, if you’ve just finished an arm workout, you get away with 20 grams of protein if you’re young. If you’re older, maybe 60 or above, you should try to get twice that amount for optimal gains.20

Given that the amount of protein required to maximize muscle protein synthesis seems to be around 20-30 grams, it might be a good idea to spread your daily protein intake into smaller meals throughout the day instead of loading up on a few hefty meals. 21

When amino acid levels in your blood are elevated over long periods of time, you actually stop building muscle. This is called the “muscle-full”-effect. While eating one or two large meals a day might not be optimal, neither is constant sipping on a protein shake. You need some time between meals, but not too long if you want to optimize your chances to build muscle. A compromise between one or two large meals and constant snacking might be the best option. Spread your total protein intake out over the day into moderate-sized servings, maybe every third or fourth hour. This should maximize the anabolic response to each meal.

If this all sounds like too much fiddling about and minutiae for your liking, don’t bother with it. If you prefer a few large meals instead of a lot of smaller ones, it’s not the end of the world. It might not be optimal, but you’ll still be able to build muscle. There are plenty of real-world examples of people who practice intermittent fasting, for example, who get great results.

Read more: How Much Protein from a Single Meal Can Your Body Use to Build Muscle Mass?

Protein Timing

When you haven’t eaten for a while, like in the morning when you wake up, your muscle protein breakdown is greater than your muscle protein synthesis. In other words, you lose muscle when you fast. This sounds worse than it is. This balance between synthesis and breakdown goes up and down depending on what you do and when you eat. It all evens out in the end.

After strength training, muscle protein increases even if you don’t eat or drink any protein. However, muscle protein breakdown remains greater than muscle protein synthesis. Only once you give your muscles what they crave: protein, does that balance switch and you actually start building muscle.

If you fast for some reason, the fact that your workout boosts muscle protein synthesis means that you lose less muscle during your fast. You won’t increase your muscle mass until you break the fast and eat something, though.22

The combination of eating protein and working out builds more muscle than either eating or training alone. The combination of training and protein creates a larger effect than if you added them together on their own. One plus one is greater than two, in this case.

Early studies examining the effects of post-exercise protein used free amino acids, but later research shows that you get the same effect from regular protein. Protein supplements like whey protein powder and food sources like eggs, beef, soy, and whole milk all work fine as part of your post-exercise meal.

The effect of a protein shake over the course of a few hours after a training session is one thing. Whether that effect translates into bigger and stronger muscles over time is another one entirely. Some studies suggest greater increases in strength and improved body composition with a protein-rich meal or a protein shake immediately after workouts. Other studies fail to see a difference. The same amount of protein but at some other time during the day has the same effect.

One meta-analysis found that you build more muscle if you eat protein within an hour after finishing a workout compared to waiting longer. However, it also noted that you only get this effect if you add that protein-rich meal to your regular protein intake. Just re-distributing the protein you normally eat makes no difference. In studies showing greater muscle growth in participants eating or drinking protein right after a workout, those participants also eat more protein as a whole than participants in the control groups. With a matched total protein intake between groups, that advantage for post-exercise protein disappears.23

When you eat or drink something with plenty of protein, large amounts of amino acids appear in your blood. This tells your body to start building new muscle protein. Currently, it is unclear if a protein intake right after a workout is any better than consuming the same amount of protein at some other time, regardless of what supplement manufacturers tell you. To be on the safe side, though, why not take the opportunity to give your muscles what they need when you’re done in the gym?

Protein Before or After a Workout

Your muscles can use the protein you eat either before or after a workout. It doesn’t seem to matter much. You get the boost in muscle protein synthesis regardless. Not many studies have examined the effects of protein before a workout on long-term results, but in one study from 2017, participants who consumed 25 grams of protein right before working out ended up with similar results as participants who consumed the same amount of protein but immediately after training.24

If one protein-rich meal before or after a workout means gains, two meals, one before and one after training, must mean twice the gains, right? Unfortunately, there is no research on this subject. It won’t hurt, so “bracket” your workouts between two protein intakes if you want. It’s not certain that your muscle will grow any more from this practice, though.

Training without eating anything, for example before breakfast, is a viable option. Maybe you don’t have any other time for working out, or maybe you just prefer to train on an empty stomach. If you train before you eat anything at all, it’s probably a good idea to eat or drink some protein reasonably soon after your workout. Until you do, you won’t switch muscle breakdown to muscle gain. If you work out fairly soon after a protein-rich meal, you don’t have to worry about that. You already have enough amino acids from that meal available, meaning that even more protein probably won’t do much.25

Again, the total amount of protein you eat over a day is the most important factor, by far. However, the way you time your meals around a workout might give you some extra benefits. The research on the subject is lacking. Your muscles are more sensitive to any protein you eat for up to 24 hours after a strength training session, so a minute or even an hour likely makes little difference.26

You benefit from the combined effects of training + protein for many hours after training, so you’re not in any huge hurry. These effects are most likely the greatest the first few hours after a workout, though, so don’t delay your protein intake for hours on end if you don’t have to.

Protein Sources

The foods with the most high-quality protein come from the animal kingdom, like meat from cattle, fish, poultry, seafood, and game. Good animal-based protein sources also include foods from animals, such as dairy and eggs. There are also plenty of plant-based foods that provide a lot of protein, like legumes, nuts, and seeds, although these are, with few exceptions, not as good, at least not on their own. Animal sources of protein are the ones containing the highest amounts of essential amino acids, the amino acids you need to start building muscle.

The amino acid l-leucine is the one responsible for starting the muscle-building processes when you eat protein. Animal protein sources give you more leucine than vegetable sources. If you want to send powerful signals to your body to build as much muscle as possible, you need around 3 grams of leucine from a particular meal.27 This is called the “leucine threshold”.

This means that plant-based protein sources don’t build as much muscle as animal-based ones. On a gram-for-gram basis and if you only eat that protein source and nothing else, that is. If you don’t eat any animal-based products, don’t worry. You’ll still be able to get stronger and build muscle from your workouts. You have a couple of options, including simply eating more of the vegetable protein to get more leucine.

For example, you need to eat 38 grams of pea protein, 40 grams of soy protein, or a whopping 54 grams of hemp protein to get the same anabolic effect as you get from 25 grams of whey protein. You can also combine several plant-based proteins. That way, they complement each other and you stimulate your muscle protein synthesis without the need for huge protein feedings.28 A classic example is rice and beans.

The average person doesn’t have to think about combining different protein sources in a single meal. It all works out over the course of the day, as long as your diet is reasonably varied. 29 However, as a strength athlete or a bodybuilder, you might want to make sure you get some high-quality protein every meal.

If you, for some reason, get too little protein from a particular meal, meaning you don’t get enough leucine to get a proper anabolic response from your muscles, you can rescue the situation by adding leucine to the meal in question.30 However, it probably makes more sense for most people to make sure each meal provides enough protein.

Most research looking at protein ingestion with strength training focuses on protein supplements. These include whey protein, casein protein, soy protein, beef protein, pea protein, and egg protein. They all work fine following a training session. Although leucine-rich proteins like whey stimulate muscle protein synthesis a little better, you can probably get the same effect from a larger serving of a protein with less leucine, like soy.

In the long run, the dairy proteins whey and casein could lead to greater gains than, for example, soy protein, when similar amounts of protein are consumed, according to some studies.31 Again, simply increasing the amount of protein per serving, if you use soy or another vegetable-based protein supplement should eliminate that difference. In fact, a 2018 meta-analysis finds that athletes using soy protein gain just as much muscle mass and strength as those who use whey protein.32

Can you eat a regular protein-rich meal instead of drinking a protein shake after a workout? Sure you can. Protein is protein. While a protein supplement might be more convenient after a training session, protein from regular food also give your muscles the building blocks they need.

The amount of research on whole or “real” foods after strength training is pretty limited, but two studies show that it works fine.33 34. In one of these, whole milk was better than skim milk. In the other study, the participants built more muscle from whole eggs compared to egg whites, even though the researchers matched the protein content of the meals.

Building muscle isn’t everything, and a healthy diet also provides you with fats, carbohydrates, vitamins, and minerals in addition to various protein sources. When convenience demands it, such as following a training session, protein supplements are a convenient and effective alternative.

Protein Safety

The safety of high-protein diets, including potential issues like kidney damage and loss of calcium, has been a concern for many decades. These worries are still common, even though no evidence suggests harmful effects of a high-protein intake, as long as you are healthy. Results from studies on renal patients aren’t entirely relevant when evaluating the effects of protein on healthy kidneys, for example.

The World Health Organization has published reports indicating that there is no evidence linking protein intake to renal disease.35

Short-term studies show that a protein intake of 3-4 grams of protein per kilogram of body mass per day does not have any negative effects. A year-long study did not show any harmful effects on liver function, kidney function, or blood lipids when the participants consumed 3.3 grams of protein per kilogram of body mass per day.36

Recent epidemiological studies suggest that a high (>20% of the energy intake) protein intake might increase the risk of cancer and type 2 diabetes. However, these studies only observe associations. They do not show cause-and-effect. Also, they don’t take into account the quality of the protein sources. Processed meats, for example, are known to be bad for you and considered to be carcinogenic, meaning too much of them can give you cancer.

Key Points

  • Protein is the most important nutrient for building muscle.
  • Protein is made up of amino acids. Out of these, you need to get enough of the 9 essential ones through your food.
  • The average person needs at least 0.8 grams of protein per kilogram of body weight and day. Preferably 1.2 grams per kilogram.
  • If you’re looking to build muscle, you should aim for at least 1.6 grams of protein per kilogram of body weight and day. If you want to be sure you get enough, you can aim for 2.2 grams per kilogram.
  • When on a weight-loss diet, the amount of protein you need to prevent muscle loss increases. It could be as high as 2.7 grams of protein per kilogram of body weight and day.
  • A daily protein intake as high as 3.3 grams per kilogram for up to a year has no negative effects.
  • Your total protein intake is the most important thing to consider, by far. Things like protein timing and protein distribution might offer some additional, but much smaller, benefits.

Take-Home Message

Protein is important. Make sure to consume enough of it.

Use our protein calculator to estimate your daily protein need.

More reading:


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  2. J Nutr Biochem. 1999 Feb;10(2):89-95. Nonessential amino acids are not necessary to stimulate net muscle protein synthesis in healthy volunteers.
  3. J Nutr. 2006 Feb;136(2):525S-528S. Skeletal muscle protein metabolism and resistance exercise.
  4. Int J Sport Nutr Exerc Metab. 2007 Aug;17 Suppl: S47-57. Role of amino acids and peptides in the molecular signaling in skeletal muscle after resistance exercise.
  5. Am J Physiol Endocrinol Metab. 2007 Sep;293(3):E833-42. Coingestion of carbohydrate with protein does not further augment postexercise muscle protein synthesis.
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  18. Physiol Rep. 2016 Aug;4(15). The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein.
  19. J Am Diet Assoc. 2009 Sep;109(9):1582-6. A moderate serving of high-quality protein maximally stimulates skeletal muscle protein synthesis in young and elderly subjects.
  20. Agro Food Industry Hi Tech 24(2):35-38 · March 2013. Whey protein ingestion enhances muscle protein synthesis in aging males.
  21. J Int Soc Sports Nutr. 2017 Jun 20;14:20. International Society of Sports Nutrition Position Stand: protein and exercise.
  22. J Nutr. 2006 Feb;136(2):525S-528S. Skeletal muscle protein metabolism and resistance exercise.
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  26. The Journal of Nutrition, Volume 141, Issue 4, April 2011, Pages 568–573. Enhanced Amino Acid Sensitivity of Myofibrillar Protein Synthesis Persists for up to 24 h after Resistance Exercise in Young Men.
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  31. The American Journal of Clinical Nutrition, Volume 85, Issue 4, April 2007, Pages 1031–1040. Consumption of fluid skim milk promotes greater muscle protein accretion after resistance exercise than does consumption of an isonitrogenous and isoenergetic soy-protein beverage.
  32. International Journal of Sport Nutrition and Exercise Metabolism. No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance Exercise.
  33. Medicine & Science in Sports & Exercise. 38(4):667-674, Apr 2006. Milk Ingestion Stimulates Net Muscle Protein Synthesis following Resistance Exercise.
  34. Am J Clin Nutr. 2017 Dec;106(6):1401-1412. Consumption of whole eggs promotes greater stimulation of postexercise muscle protein synthesis than consumption of isonitrogenous amounts of egg whites in young men.
  35. Protein and amino acid requirements in human nutrition. Report of a joint FAO/WHO/UNU expert consultation (WHO Technical Report Series 935).
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