While strength training is important for building muscle, consuming the right amount of protein is also important. There has been ongoing research and debate about how much protein is needed to optimize muscle growth. In this Nutrition feature, we discuss current research evaluating protein's role in muscle growth and how much a person should consume each day.

Protein is found in every cell and tissue in the body. Although it has many vital roles in the body, protein is crucial for muscle growth as it helps repair and maintain muscle tissue.

The recommended daily amount to be taken from the diet to prevent protein deficiency in adults who do not do active sports or do not do physical strength is 0.8 grams of protein per kilogram of body weight . However, more recent research shows that individuals trying to build muscle need more than this.

Consuming less protein than the body needs has been associated with decreased muscle mass. In contrast, protein intake above the daily recommended amount can help increase strength and lean body mass when combined with exercise . In addition, it is very important for wound healing and patients with chronic diseases such as cancer to maintain muscle mass by taking adequate protein.  

Why Is Protein Important for Muscle Building?

Protein consists of amino acids that serve as building blocks for cells and tissues in the body. There are 20 amino acids that combine to form proteins .

Some of them can be synthesized by the human body, while some cannot. The nine amino acids that the body cannot make are called essential amino acids. These must be obtained through diet. When a person eats protein, it is digested and broken down into amino acids that are involved in many processes in the body, including tissue growth and repair, immune function, and energy production.

Like other body tissues, muscle proteins are constantly broken down and rebuilt. To build muscle, a person needs to consume more protein than is broken down. Because protein is high in nitrogen, this is often referred to as a net positive nitrogen balance.

If a person does not consume adequate amounts of protein, their body tends to break down muscles to provide the body with the amino acids needed to support body functions and protect more important tissues. Over time, this can lead to a decrease in muscle mass and strength.

Finally, the body uses amino acids for muscle protein synthesis (KPS), which is the primary driver of muscle repair, recovery, and growth after strenuous exercise.




How Much Protein Do You Need to Build Muscle?

According to the US 2020-2025 Dietary Guidelines, most healthy adults over the age of 19 should get 10-35% of their daily calories/energy from protein. One gram of protein provides 4 calories. This means that a person consuming 2,000 calories per day should consume 50 to 175 grams of protein per day.

The current daily recommended allowance for protein of 0.8 grams per kg of body weight is based on the amount needed to maintain nitrogen balance and prevent muscle loss. However, it may not be appropriate to extend these recommendations to active individuals who want to build muscle.

When it comes to building muscle mass, the ideal daily amount of protein a person should consume varies depending on a variety of factors, including age, gender, activity level, health, and other variables. However, several studies have given us a good idea of ​​how to calculate the amount of protein adults need to increase muscle mass based on body weight.

What Does Scientific Research Say?

While most studies agree that higher protein intake is associated with improvements in lean body mass and strength when combined with resistance exercise, the optimal amount of protein needed to build muscle is controversial.

Here's what the latest research says about this:

A 2020 meta-analysis published in the journal Nutrition Reviews found that protein intakes ranging from 0.5 to 3.5 g per kilogram of body weight can support increases in lean body mass.

The rate of increase in lean body mass resulting from higher protein intake decreased rapidly after 1.3 g per kg of body weight was exceeded. Strength training suppressed this decline. This suggests that increasing protein intake with strength training is best for gaining lean body mass. So, taking more than a certain amount of protein seems to do more harm than good. Additionally, when protein intake increases, it must be supported with exercise.

Another 2022 meta-analysis published in the journal Sports Medicine concluded that a higher protein intake of approximately 1.5 g “per kilogram” of body weight per day should be paired with resistance training for optimal effects on muscle strength . The researchers noted that the benefits of increased protein intake on strength and muscle mass appear to plateau between 1.5 and 1.6 g per kilogram of body weight per day.

Finally, a 2022 systematic review and meta-analysis published in the Journal of Cachexia, Sarcopenia and Muscle concluded that a protein intake of 1.6 g or higher per kilogram of body weight per day resulted in small increases in lean body mass.

Notably, 80% of the studies reviewed in this review reported that participants consumed at least 1.2 g of protein per kilogram of body weight per day, which is still higher than the current daily recommended amount. This may be a potential contributor to the attenuated effects of protein intervention with resistance training in older adults.

Although it's difficult to give exact numbers due to varying study results , the optimum amount of protein for building muscle appears to be between 1.2 and 1.6 g per kilogram of body weight .




What are the Best Sources of Protein?

A person can meet his daily protein needs by eating animal and plant protein sources.

Animal-based protein sources include:

Plant-based protein sources include:

Some nutritionists consider animal protein sources to be superior to plant-based protein sources when it comes to building muscle mass. This is because they are complete proteins and contain sufficient amounts of all the essential amino acids the body needs. It is also easy to digest.

Some experts consider most plant proteins to be incomplete proteins because they do not contain all essential amino acids. However, individuals can match missing protein sources to create a complete protein. Examples include rice and beans, hummus and pita bread, or peanut butter on whole wheat bread.

Doctors generally agree that healthy adults can safely tolerate long-term protein intake of up to 2 g per kilogram of body weight per day without any side effects. However, some groups of people, such as healthy, well-trained athletes, can tolerate up to 3.5 g per kilogram of body weight.

Most research suggests that eating more than 2 g of protein per kilogram of body weight per day can cause health problems over time.



Is There Any Harm in Excess Protein Intake?

Symptoms of excessive protein intake include:

More serious risks associated with chronic protein overconsumption include:

Summary

When combined with resistance exercise, it can support protein intakes above the current daily recommended amount.

The best way to meet your daily protein needs is to consume lean meat, fish, beans, nuts and legumes.

Because the optimal amount of protein a person needs depends on age, health status, and activity level, speaking with a healthcare provider or registered dietitian to discuss how much protein is appropriate for you should be considered.