Muscle is made up of mostly protein, so it’s no surprise that a high-protein diet can help you build more of it. Exactly how much protein per day you need is debatable. Common bodybuilding advice suggests eating one gram of protein per pound of bodyweight to support muscle growth, however, the science behind this recommendation varies depending on age, fitness level, and overall body composition goals.

Based on the existing research, here’s how much protein you should be eating to build muscle. 

How Protein Supports Your Muscles

Protein is made up of amino acids that act as building blocks for your body’s cells and tissues — including muscle mass — which means that your muscle is made up of protein. 

These amino acids are essential for supporting numerous bodily functions. If you aren’t getting the required (essential) nutrients — like amino acids — through food, your body doesn’t have what it needs, resulting in compromise. This involves stealing amino acids that are stored in your body (in your blood and muscle tissue), which can lead to muscle loss over time. 

Muscle Protein Synthesis (MPS) Vs. Muscle Protein Breakdown (MPB)

Amino acids are also used for muscle protein synthesis (MPS), or the process of repairing and maintaining muscles after intense use. 

Related: How to Build Muscle: What to Eat, How to Train, and More

Muscle use during training or strenuous activity creates micro-tears that lead to muscle protein breakdown (MPB). Amino acids are then shuttled to your muscles to start repairing the damaged tissue and synthesizing new tissue to replace it. 

This process doesn't automatically lead to bigger muscles, but it can make your muscles stronger or cause them to adapt to the type of training that caused the tears in the first place. 

MPS explains why protein — and strength training, in particular — are so essential for maintaining and building lean body mass. 

Muscle Growth

When it comes to building muscle, the amount of protein you eat is a considerable factor. With the role of amino acids in muscle protein synthesis, maintaining a positive protein balance (in other words, eating more protein than you are breaking down or using) is one part of the muscle-building equation. 

Muscle growth occurs when MPS outpaces MPB. 

This can be achieved through a combination of increased protein intake, a strategic strength training routine, adequate rest (this is when MPS occurs), and often plenty of calories to support weight gain overall. 

Depending on individual factors, such as fitness level and starting body composition, it is also possible to lose fat and gain muscle at the same time. However, this is not ideal for everyone and your rate of muscle growth is significantly less than following a standard weight-gain approach. 

How Much Protein Do You Need to Gain Muscle?

Your protein needs are most directly related to your muscle mass: The more you have and the more you use it, the more protein you need. Age and fitness level can also impact how much protein is required to promote muscle growth. 

Bodybuilders and weightlifters have higher protein needs because they are looking to add mass and are simultaneously using their muscles more than the average person or non-lifter. 

Of course, it is entirely possible to overdo it. Eating too much protein can negatively impact your ability to build muscle by limiting your intake of other important macros for bulking (healthy fats and carbohydrates) that support your training and weight gain. Getting the right amount for your individual requirements is crucial to obtaining the best results. 

Related: The Dark Side of Excessive Protein

Many fitness enthusiasts recommend about one gram of protein per pound of body weight, but this likely isn’t a perfect approach for everyone, and the research varies on this topic depending on age, fitness level, and overall body composition goals.  

What the Science Says

Some older studies suggest that an intake of at least 1.6 to 1.7 grams per kilogram of body weight (0.7 to 0.8 grams/pound) is needed to maintain lean mass with strength training. But more recent studies suggest intakes as high as 1.8 to 2.0 grams per kilogram of body weight (0.8 to 0.9 grams/pound). 

A larger and more recent review of the research even determined that for most, there aren't any beneficial effects of eating more than 1.6 grams of protein per kilogram (or 0.72 grams per pound) of body weight. 

Related: 5 Ways to Eat More Calories When You're Trying to Bulk Up

All of these recommendations fall within the range suggested by the American College of Sports Medicine, which suggests 1.2 to 2.0 grams per kilogram of body weight (0.54 to 0.9 grams/pound). For reference, this would translate to 81 to 136 grams for a 150-pound adult.

Your ideal protein needs can also depend on your overall calorie intake. 

Your macro ratio may have an impact on body composition when looking at a surplus or restriction of calories. A narrative review of the research and smaller studies have suggested that higher protein intakes between 2.2  to 3.4 grams/kilogram (1 to 1.5 grams per pound of body weight) during a large calorie surplus (to promote weight gain) results in lower gains in body fat, promoting more muscle overall. 

The Verdict

Based on the averages from evidence-backed recommendations, a general rule for maintaining existing muscle is to eat roughly 0.8 to 1 grams of protein/pound of body weight. This amount may increase as high as 1 to 1.5 grams/pound when looking to add lean mass using a calorie surplus. 

How to Get Enough Protein 

Once you know your daily protein needs, the next step is finding the best sources of protein to eat. These include lean meats, fish, dairy, and plant-based options. 

Related: How to Start a Food Journal That Turns Motivation Into Discipline

Next, learn how to portion your food choices to match your macros and start tracking your daily intake to ensure you are staying consistent. 

This article was originally published on TrifectaNutrition.com.