When talking about “weight loss,” fat and carbs have their fair share of haters, but protein is always getting good press.  

The world of weight loss can be a battlefield, with fat and carbs often taking the brunt of the blame. However, there's one nutrient that always seems to come out on top - protein. This powerhouse nutrient is crucial for building strong bones, muscles, and healthy skin, among many other vital bodily functions. When you consume protein, your body goes to work breaking it down into amino acids that help shuttle molecules throughout your system, promoting muscle growth, and even boosting your metabolism. It's no wonder protein always seems to get the good press!

But if that means more protein is always better? To figure out that problem, you need to know the principles of how proteins are metabolized and utilized in the body. Here’s what the research and studies show about optimal protein intake

Why is Protein Important

Protein is found throughout the body and is a component of every cell.

• Tissue building is the primary function of the protein. It is an essential building block of all bones, muscles, cartilage, hair, and skin. 
• Protein also helps repair body tissues, infection-fighting, blood clotting, and wound healing. 
• It is the necessary raw material from which your body makes the enzymes critical for promoting stomach acid and aiding digestion.
• Red blood cells contain a protein compound that helps oxygenate body organs and tissues while supplying nutrients like fats, vitamins, and minerals to the entire body.
• Protein also plays a vital role in hormone regulation.
• Your body needs protein to produce antibodies to fight against viruses, bacteria, and other harmful substances. A high-protein diet can help strengthen your immune system.  

How Much Protein Do We Need Every Day?

According to the World Health Organization and the United Nations Agrifood Organization, the optimal protein intake for a healthy adult is 0.83 grams/kg of body weight per day. So, for example, the daily protein requirement for a 60 kg adult is 49.3 g per day.

According to the Food and Nutrition Board of the Institutes of Medicine (IOM), an acceptable protein intake range for adults is 10%-35% of total calories, or 1.2 to 1.8 g/kg body weight for protein, depending on the level of physical activity. In other words, a physically active adult with a daily intake of 2,000 kcal per day should get 200-700 kcal from protein. That’s equivalent to 50-175 grams of protein.

According to the U.S. Department of Agriculture’s MyPlate website, daily protein requirements differ vastly by age. Here are the suggested amounts of protein based on factors like age, gender, and activity level.

What Food Contains Protein

Protein can be found in animal sources and plant-based foods. Some foods are considered healthy and excellent sources of protein, including eggs, nuts, lean meats, fish, dairy, and certain grains. Eating plans that include healthy-fat dairy products may help improve blood pressure, heart health, and cholesterol levels.

Here are some options for nutritious high-protein food:

• Poultry: Egg, chicken breast, lean beef, lean pork, turkey breast, lamb, goat, skinless chicken, quail, and duck.
• Seafood: fish, shellfish, salmon, tuna, cod, shrimp, mackerel, lobster, catfish, crab
• Dairy foods: cottage cheese, greek yogurt, milk, cheese.
• Legumes: lentils, beans, split peas, soy.
• Nuts and seeds: almonds, peanuts and peanut butter, quinoa, pumpkin seeds, Ezekiel bread,  chia seeds, walnuts. 

Some high-protein food may also be high in saturated fat. High intake of saturated fat can increase the risk of heart and cardiovascular disease. Thus, limit protein foods high in saturated fats.

The following amounts are considered equivalent to one ounce of protein-rich foods:

• Meat: 1 ounce of cooked lean beef, pork, or ham.
• Poultry:  1 egg; 1 ounce of chicken or turkey, without skin.
• Seafood: 1 ounce of cooked fish or shellfish.
• Beans: ¼ cup cooked beans.
• Nuts: ½ ounce of nuts or seeds; 1 tablespoon peanut butter
• Dairy:  ⅓ cup of Greek yogurt

The Science Behind Recommended Protein Intake

The answer to how much protein should you consume each day lies in a calculation called nitrogen balance, which is calculated as the difference between N intake and N losses in urine, stool, skin, and body fluids. 

When your body is in nitrogen balance, it means that the amount of protein consumed is equal to the amount of protein used by the body. This is important for maintaining muscle mass.

The average amount of high-quality protein per day required to bring people to nitrogen balance is 0.66 g/kg. To account for individual variations and ensure that most people achieve nitrogen balance, the recommended daily protein intake is often bumped to around 0.83 g/kg. 

However, the nitrogen balance test assumes we're eating high-quality protein. Therefore, it's best to consume around 1.05 g/kg of protein per day to ensure adequate protein intake for most individuals.

Is it Possible to Eat Too Much Protein?

Yes, it is possible to eat too much protein. 

In fact, consuming too much protein could place additional strain on the kidneys since must work harder to remove the waste products that result from the breakdown of protein. Over time, this can cause kidney damage or even kidney failure in people who are predisposed to kidney disease.

Another potential consequence of consuming excessive amounts of protein is that it can lead to weight gain. While protein is an important nutrient for building and maintaining muscle mass, consuming more protein than your body needs will lead excess calories to being stored as fat. 

Consuming too much protein can also cause digestive issues like constipation, bloating, and diarrhea. This problem is common among people who consume protein supplements.

The Bottom Line

• The recommended protein intake is derived from nitrogen balance studies.
• Eating between  0.83 grams of protein per kilogram of body weight per day will meet most peoples’ protein needs.
• There is no proven health benefit to a protein intake of more than 2g/kg/d.

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