To build muscle mass, you need around 1.2–1.7 grams of protein per kilogram of body weight (g/kg) or 0.5–0.8 grams per pound of body weight. However, your protein needs depend on many factors, such as your health goals, activity level, weight, and age.
While protein is essential for muscle growth and repair, there are risks associated with consuming too much.
How Much Protein Do I Really Need?
For adults, the recommended dietary allowance (RDA) for protein is 0.8 g/kg per day. This is designed to meet the needs of the average person without specific fitness goals who don't engage in much physical activity.
However, recent research indicates that this RDA isn't enough to support a body under stressful conditions, such as restricting calorie intake or exercising regularly. Some researchers say the RDA needs to be reevaluated.
A higher protein intake is usually recommended for people trying to build muscle. For example, athletes or individuals leading a very active lifestyle may benefit from 1.2–2.0 g/kg per day, depending on the intensity and type of exercise, age, and other factors.
Growing adolescents have higher protein demands from physical activity and growth. Older adults may also need closer to 1.2–2,0 g/kg per day to prevent lean muscle loss associated with aging.
Factors To Consider
Here are some of the most important things to consider when determining an optimal daily protein intake:
- Body composition: Individuals with larger bodies or more muscle mass typically require more protein to support muscle growth and recovery.
- Exercise intensity and type: Engaging in intense resistance or endurance training may require more protein to repair and build muscle tissue.
- Age: Older adults typically need more protein to counteract age-related muscle loss (sarcopenia).
- Gender: While not the only factor, gender can influence protein needs due to differences in muscle mass and hormonal profiles.
- Training goals: If your goal is muscle gain, your protein needs will generally be higher than if your goal was maintenance or weight loss.
- Calorie intake: If you're in a caloric surplus, your protein needs might be lower, as more overall energy supports muscle synthesis. In a caloric deficit, higher protein is recommended to preserve lean muscle.
- Protein quality: High-quality protein sources can help support muscle-building with potentially less total protein. For the most nutritional benefit, prioritize whole-food protein sources over protein supplements.
- Timing and distribution: Intentionally spreading your protein intakethroughout the day, especially before and/or after a workout and before bed, can help optimize muscle protein synthesis.
Why Protein Is Important for Building Muscle
Protein is made up of amino acids, which are often called "the building blocks" for muscle tissues.
When you do strength exercises, your muscle fibers experience very small tears that are then repaired to become even stronger. Your body builds muscles through this process, which is also known as muscle protein synthesis.
Your body needs amino acids—especially essential amino acids from dietary sources—to support the muscle-building process. Without enough protein, you won't have the necessary resources to repair and grow muscles effectively, limiting your progress.
Finally, protein intake helps prevent muscle breakdown, especially when working out intensely or going through a period of calorie restriction for any reason. For example, if someone is trying to lose weight, the goal is to drop body fat but preserve lean muscle mass.
How Much Protein Is Too Much?
For most healthy adults, a protein intake of up to around 2.0 g/kg per day is generally considered safe (possibly higher for people who are "well-adapted" to high-protein diets). However, regularly eating large amounts of protein can eventually be pointless, as your body will use what it needs and excrete or store the rest as fat.
When the body metabolizes protein, it creates waste that the kidneys must filter out. A very high-protein diet can put extra strain on the kidneys for people with existing kidney conditions and possibly people without.
Research shows that a high intake of protein from plant sources (like legumes and tofu) is less likely to pose health effects than protein from animal sources (like red meat, poultry, eggs, and dairy products).
When consumed in excess, animal-derived protein foods are significantly higher in saturated fat, a nutrient known to promote cardiovascular disease.
Symptoms of Excessive Protein Intake
Some possible symptoms and complications that can develop from regularly eating too much protein include:
- Dehydration: High protein intake may increase water loss because your kidneys work harder to process nitrogen from protein.
- Digestive issues: If protein intake is high and fiber intake is low, changes in bowel habits, like constipation or diarrhea, may occur.
- Kidney strain: Overworking the kidneys with excessive protein intake can be particularly concerning for people with preexisting kidney conditions.
- Bad breath: High-protein, low-carbohydrate diets can lead to ketosis, a state in which your body switches from using glucose to fat for energy, which often causes a distinct breath odor.
- Increased risk of heart disease: Diets high in protein from animal sources, particularly red meat, may increase the risk of heart disease as they are also high in saturated fat.
- Nutrient imbalance: Excess protein may displace other important nutrients in your diet, like fiber, vitamins, and minerals, especially if it crowds out fruits, vegetables, and grains.
- Weight gain: Consuming more protein than you need can lead to a calorie surplus, which may be stored as fat if it's not used for energy or muscle repair.
- Mood changes: High protein with insufficient carbohydrates may impact serotonin (a feel-good hormone) levels, affecting mood and energy levels.
Great Food Sources
Protein is found in almost every food (including broccoli), but some foods are better sources than others. Examples of high-protein foods are:
- Certain plant-based yogurts (made from soy or peas, especially)
- Dairy products (cheese, milk, yogurt, cottage cheese)
- Eggs
- Fish and seafood
- Legumes (beans, peas, and lentils)
- Nuts, seeds, and nut butter
- Poultry (chicken, turkey)
- Quinoa and buckwheat
- Red meat
- Seitan, a plant-based meat alternative made with vital wheat gluten
- Soy milk and pea milk
- Tofu, tempeh, and edamame
It's best to achieve your protein needs by eating a variety of these foods. If you follow a plant-based diet, it is possible to meet your protein needs from plant sources, despite the misconceptions. If you eat meat, eat both animal and plant protein sources, as plants will also provide fiber, antioxidants, and additional vitamins and minerals for health.
Other Protein Sources for Building Muscle
In addition to the protein foods listed above, many people turn to protein powders and supplements when the goal is building muscle.
Protein powders (which may be made from whey, pea, soy, or rice, to name a few) provide 20–30 grams of protein per scoop. You can add these to smoothies, mix them into your oatmeal or yogurt, or shake them up with water or your favorite milk.
These are not a requirement to "bulk up," but they are an easy way to get a substantial amount of protein in a small serving, saving you some room in your stomach for other foods and nutrients. This also means it can be easy for some people to consume more protein than their bodies need and experience side effects.
Are There Risks of Not Getting Enough Protein During Exercise?
Most people are not at risk of eating too little protein. As long as you're consuming enough calories in your diet, it is very rare to have a protein deficiency.
However, if your goal is to build muscle, an insufficient amount of protein in your diet can hinder your progress and recovery. Without enough protein, muscle breakdown may exceed muscle synthesis, leading to muscle loss instead of growth. You may also feel fatigued more often, recover more slowly from workouts, or experience more illness (a sign of a weakened immune system).
By understanding your protein needs and getting it from various healthy sources in your diet, it's usually simple to get enough to support everyday life and muscle-building goals.
Summary
Protein is a critical nutrient for supporting everyday health and specific body composition goals, like building more muscle. While most people can meet their needs with at least 0.8 g/kg per day, muscle-building generally requires more. Fortunately, protein is found in various plant- and animal-based foods.
The best way to determine your daily protein goals for building muscle is to consult with a registered dietitian, who can help tailor a plan that accounts for individual factors.
