How Much Protein Should You Eat to Build Muscle?

Strength training matters for building muscle, but so does consuming the right amount of protein. Research and debate continue over how much is needed to optimize growth. This nutrition feature discusses protein's role in muscle growth and current research on how much to consume each day.

Protein is present in every cell and tissue. Although it has many vital roles, it is particularly important for muscle growth because it helps repair and maintain muscle tissue.

For adults who do not exercise actively or perform physical work, the recommended daily allowance needed to prevent deficiency is 0.8 grams of protein per kilogram of body weight. However, newer research suggests people trying to build muscle need more .

Eating less protein than the body needs has been associated with reduced muscle mass. Conversely, intake above the recommended daily allowance, combined with exercise , may increase strength and lean body mass. Adequate protein to preserve muscle is also important for wound healing and people with chronic illnesses such as cancer.  

Why Is Protein Important for Building Muscle?

Protein consists of amino acids, the building blocks of cells and tissues. There are 20 amino acids that combine to form proteins.

Some can be synthesized by the human body, while others cannot. The nine the body cannot make are called essential amino acids and must come from food. Dietary protein is digested into amino acids involved in processes including tissue growth and repair, immune function, and energy production.

Like other tissues, muscle proteins are continually broken down and rebuilt. To build muscle, a person must consume more protein than is broken down. Because protein is high in nitrogen, this is often called a net positive nitrogen balance.

Without enough protein, the body tends to break down muscle to obtain amino acids for bodily functions and to preserve more important tissues. Over time, this can reduce muscle mass and strength.

The body also uses amino acids for muscle protein synthesis (MPS), the main driver of muscle repair, recovery, and growth after strenuous exercise.

How Much Protein Do You Need to Build Muscle?

According to the US Dietary Guidelines for 2020-2025, most healthy adults over 19 should obtain 10-35% of daily calories/energy from protein. A gram provides 4 calories. Someone consuming 2,000 calories daily should therefore eat 50 to 175 grams of protein a day.

The current recommended daily allowance of 0.8 grams per kg body weight is based on the amount needed to maintain nitrogen balance and prevent muscle loss. Applying it to active people seeking muscle growth may not be appropriate.

The ideal daily intake for building muscle varies with age, sex, activity, health, and other factors. Several studies nevertheless provide a useful basis for calculating adult needs according to body weight.

What Does Research Say?

Most studies agree that higher intake combined with resistance exercise improves lean mass and strength, but the optimal amount for muscle building remains debated.

Recent research findings include:

Nutrition Reviews published a 2020 meta-analysis finding that intakes from 0.5 to 3.5 g per kilogram of body weight could support increases in lean body mass.

The rate of lean-mass gain from higher intake fell rapidly above 1.3 g per kg body weight. Strength training suppressed this decline, suggesting that higher protein intake paired with training is best for gaining lean mass. In other words, exceeding a certain amount appears to do more harm than good. Increased protein intake must also be supported with exercise.

Sports Medicine published another meta-analysis in 2022, concluding that a higher daily intake of approximately 1.5 g per kilogram body weight should be paired with resistance training for optimal strength effects. Benefits for strength and muscle mass appeared to plateau between 1.5 and 1.6 g per kilogram daily.

Finally, Journal of Cachexia, Sarcopenia and Muscle published a 2022 systematic review and meta-analysis concluding that at least 1.6 g per kilogram body weight daily produced small increases in lean mass.

Notably, 80% of studies in this review reported participants consuming at least 1.2 g per kilogram daily, already above the current recommended allowance. This could potentially contribute to reduced effects of protein interventions with resistance training in older adults.

Although varying results make precise figures difficult to give, the optimal amount for muscle building appears to be 1.2 to 1.6 g per kilogram body weight.

What Are the Best Protein Sources?

Daily needs can be met with animal and plant protein sources.

Animal sources include:

• Lean meats (beef or lamb)
• Poultry
• Eggs
• Fish and seafood
• Dairy products
• Whey protein powders

Plant sources include:

• Beans
• Peas
• Hazelnuts
• Lentils
• Seeds
• Soy products
• Plant-based protein powders

Some nutrition specialists consider animal sources superior for building muscle because they are complete proteins, providing all essential amino acids in sufficient amounts, and are readily digestible.

Some experts consider most plant proteins incomplete because they do not contain all essential amino acids. However, complementary sources can form a complete protein, such as 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 intake of up to 2 g per kilogram body weight daily without adverse effects. Some groups, such as healthy, well-trained athletes, may tolerate up to 3.5 g per kilogram.

Most research suggests that consuming more than 2 g per kilogram body weight daily may cause health problems over time.

Can Too Much Protein Be Harmful?

Signs of excessive intake include:

• intestinal discomfort
• nausea
• dehydration
• fatigue
• weight gain
• headache

More serious risks associated with chronic overconsumption include:

• heart disease
• epileptic seizures
• kidney and liver damage
• gout

Summary

Protein intake above the current recommended daily allowance may support muscle building when combined with resistance exercise.

The best way to meet daily needs is to eat lean meat, fish, beans, hazelnuts, and pulses.

Because optimal intake depends on age, health, and activity, consider discussing an appropriate amount with a healthcare provider or registered dietitian.