The amount of protein an individual needs depends on their age and sex. However, most adults on a 2,000-calorie diet require 50 grams (g) of protein daily.
Protein is a part of every cell in the body and a major component of the skin, muscles, bones, organs, hair, and nails. It helps the body build and repair cells and tissues.
Most people in the United States get enough protein from their diets to meet their needs.
A note about sex and gender
Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Learn more.
As a general target, the Food and Drug Administration (FDA) recommends that adults consume 50 g of protein per day as part of a 2,000-calorie diet. However, a person’s daily target may be higher or lower depending on their calorie intake.
The
| Age | Protein RDA |
|---|---|
| Children ages 1 to 3 | 13 g |
| Children ages 4 to 8 | 19 g |
| Children ages 9 to 13 | 34 g |
| Females ages 14 to 18 | 34 g |
| Males ages 14 to 18 | 52 g |
| female adult ages 19+ | 46 g |
| male adult ages 19+ | 56 g |
Many factors can affect how much protein a person needs, including their activity level, weight, height, and whether they are pregnant.
Other variables include the proportion of amino acids available in specific protein foods and the digestibility of individual amino acids.
The USDA provides a calculator to help people work out how much protein and other nutrients they need.
Protein and calories
Protein is a source of calories. Generally, protein and carbohydrates contain 4 calories per gram, while fats contain 9 calories per gram.
Most people in the U.S. meet their daily protein needs. On average, men get
Protein is one of three macronutrients which the body needs in larger amounts. The other two are fat and carbohydrates.
Protein consists of long chains of amino acids. There are 20 amino acids. The specific order of amino acids determines the structure and function of each protein.
The 20 amino acids that the body uses to create protein are:
- alanine
- arginine
- asparagine
- aspartic acid
- cysteine
- glutamic acid
- glutamine
- glycine
- histidine
- isoleucine
- leucine
- lysine
- methionine
- phenylalanine
- proline
- serine
- threonine
- tryptophan
- tyrosine
- valine
Nine essential amino acids do not experience synthesis in the human body, so they must come from the diet.
Proteins may be complete or incomplete. Complete proteins contain all essential amino acids. Animal products, soy, and quinoa are complete proteins.
Incomplete proteins are proteins that do not contain all essential amino acids. Most plant foods are incomplete proteins, including beans, nuts, and grains.
People can combine incomplete protein sources to create a meal that provides all essential amino acids. Examples include rice and beans or peanut butter on whole wheat bread.
What does protein do in the body?
Protein is present in every body cell, and an adequate protein intake is essential for keeping the muscles, bones, and tissues healthy.
Protein plays a role in many bodily processes, including:
- blood clotting
- fluid balance
- immune system responses
- vision
- hormones
- enzymes
Protein is essential for growth and development, especially during childhood, adolescence, and pregnancy.
Nutrition resources
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Protein deficiency due to a low protein intake in the diet is unusual in the U.S.
However, a lack of protein in other countries is a serious concern, especially in children. Protein deficiency can lead to malnutrition, such as kwashiorkor and marasmus, which can be life threatening.
Protein deficiency can arise if a person has a health condition, including:
- an eating disorder, such as anorexia nervosa
- certain genetic conditions
- advanced stages of cancer
- difficulty absorbing nutrients due to a health issue such as irritable bowel syndrome (IBS) or gastric bypass surgery
Very low protein intake can lead to:
- weak muscle tone
- edema or swelling due to fluid retention
- thin, brittle hair
- skin lesions
- in adults, a loss of muscle mass
- in children, growth deficits
- hormone imbalances
According to the
The guidelines classify the following foods as protein foods:
Dairy products like milk, cheese, and yogurt also contain protein. Whole grains and vegetables contain some protein, but generally less than other sources.
Animal products tend to contain higher amounts of protein than plant foods, so people following a vegetarian or vegan diet may need to plan their meals to ensure they meet their protein needs.
A person can check the label if a food product is high or low in protein. Foods that provide 5% or less of a person’s daily value (DV) are low in protein. Foods with 20% DV or more are high in protein.
A person does not need to consume foods containing all the essential amino acids at each meal because their bodies can use amino acids from recent meals to form complete proteins. Eating various protein foods throughout the day is the best way for a person to meet their daily protein needs.
Read about some healthful high protein foods here.
Some diets recommend eating more protein to lose weight.
Several studies and reviews show that following a high protein diet may encourage weight loss. Still, researchers need further studies to establish how to implement such a diet effectively.
When increasing protein intake, it is essential to ensure that the diet still contains adequate fiber, such as fruit, vegetables, and whole grains.
Replacing processed foods and sources of unhealthful fats or sugar with protein can promote a healthful diet.
Before making significant changes to their diet, it is a good idea for a person to talk with their doctor about the best strategies and tips.
Read about high protein diets here.
Protein shakes and protein powders contain high amounts of protein. Protein powders typically contain 10–30 g of protein per scoop. They may also contain added sugars, flavorings, vitamins, and minerals.
Protein in protein shakes or powders can come from:
- plants, such as peas or soybeans
- milk, such as casein or whey protein
- eggs
Building and repairing muscle requires protein. Many athletes and bodybuilders use protein products to boost muscle growth.
A wide range of protein supplements is currently available, many of which claim to encourage weight loss and increase muscle mass and strength.
However, protein shakes and powders are dietary supplements, so the Food and Drug Administration (FDA) does not regulate them. This means people cannot guarantee that the products contain what the manufacturer claims they do.
Some supplements may contain banned or unhealthy substances, such as heavy metals or pesticides.
Many protein products are high in added sugar and calories, which can lead to spikes in blood sugar and weight gain, so it is important to check the labels.
Most people, including athletes, can get enough protein from a balanced diet without supplements. Getting too much protein consistently will not provide any additional health benefits and may contribute to serious health problems, such as kidney issues.
Some people may benefit from using protein powder to address health concerns, including those with:
- a reduced appetite, which may result from older age or cancer treatment
- a wound that is not healing well, as protein can help the body repair and replace cells
- a medical condition, such as a severe burn, that requires additional calories and protein
A varied and healthful diet will provide enough protein for most people. For the best health benefits, a person can derive protein from a variety of sources, including fish, meat, soy, beans, tofu, nuts, and seeds.
Here are some suggestions for adding more protein:
- Replace regular snacks with high protein snacks, such as nuts, roasted chickpeas, and peanut butter.
- Add beans and peas to soups, side dishes, or salads. These also make great main dishes.
- Include one high protein food with each meal.
- Replace a source of carbohydrates with a source of protein, such as swapping out a piece of toast for an egg in the morning.
- Before adding protein bars to the diet, check the labels, as they can be high in sugar.
To limit fat intake while increasing protein intake, choose lean meat, poultry, and dairy products, or trim the fat before eating. Try using cooking methods, such as grilling, that do not add extra fat.
Avoid processed meats and other processed foods, which can negatively affect health. Choose nutrient-rich foods instead of processed foods when possible.
How much protein does a person need to avoid protein deficiency?
Most adults on a 2,000-calorie diet require 50 grams (g) of protein daily.
Is having 2 eggs a day enough protein?
2 eggs equal around 12 g of protein, a bit less than a quarter of a person’s daily intake. Pairing eggs with other protein sources, such as lean meats, can help increase the overall protein intake.
What are the signs of a protein deficiency?
Signs of a protein deficiency include weak muscle tone, swelling in the body, and thin, brittle hair.
Protein is an important part of every diet. The FDA recommends that adults consume 50 grams (g) of protein per day as part of a 2,000-calorie diet, though a person’s specific needs depend on their age, sex, activity levels, and other factors.
Most people in the U.S. meet their daily protein needs. If a person wants to increase their protein intake, they can include healthful, high protein foods with each meal.
Q:
Is it dangerous to use protein shakes and whey protein in a weight-loss diet?
A:
Protein shakes and whey protein are acceptable to incorporate in a healthy weight-loss diet plan, as long as the total daily protein intake does not consistently exceed a person’s recommended daily allowance for protein, and as long as a person is replacing other sources of calories with proteins, and not simply adding extra calories to their day.
Greatly exceeding protein needs can be damaging to a person’s health, including kidney damage and dehydration.
Katherine Marengo LDN, RDAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.