How much protein do you really need? Here’s how to calculate it

If you were to survey people about the most important macronutrient, you will likely find most people will answer protein. Although there are important benefits of all three macronutrients — protein, carbohydrates, and fats — and some unique functions of each, protein certainly plays numerous physiological roles that neither fats nor carbohydrates can replicate. 

For this reason, it’s important that your diet contains enough proteins for your body size and activity level, but how much protein do you really need? How do you calculate your protein requirements? In this article, we will briefly discuss protein’s many roles in the body, daily protein recommendations for adults, and how to calculate how much protein you need to eat in a day.

Why is it important to eat protein?

Protein is one of the three primary macronutrients in the diet, along with carbohydrates and fats.

Proteins are molecules composed of amino acids connected together in various linear sequences and three-dimensional geometric arrangements, depending on the specific type of protein.

Interestingly, despite the fact that there are thousands of different proteins in the human body, there are actually only 20 unique amino acids that form the building blocks of these thousands of different end products. Essentially, each of the 20 amino acids serves as a letter in the “proteins alphabet,” and different combinations of these “letters“ spell out all the different proteins your body needs, just like regular letters provide our entire dictionary of unique words.

Of the 20 amino acids, nine are considered essential amino acids because the body cannot manufacture them internally, meaning that you have to consume them through your diet.

In addition to providing four calories per gram, protein has many other functions in the body, including the following:

• Forming muscle tissue, including skeletal muscles, smooth muscles, and cardiac (heart) muscle
• Supporting tissue growth and repair
• Forming structural components of cells and tissues, such as collagen, elastin, and keratin
• Forming hormones
• Forming enzymes that catalyze biochemical reactions
• Transporting nutrients into and out of cells
• Providing calories (energy) to the cells and tissues of the body, especially during vigorous exercise or fasting
• Forming immunoglobulins (antibodies), which are immune system molecules that help fight infections
• Maintaining the pH balance in your body
• Regulating fluid balance in the body

How much protein do you need to eat in a day?

Given all the many roles of proteins in the body, it’s clear that it should be an important part of your diet, but how much protein do you need to eat per day?

The daily value (DV) of any nutrient is an established value that represents the average intake that works for most people. The daily value for protein for adults is 50 grams per day. This equates to 200 calories of protein. However, it should be noted that this is much less protein than most adults in the United States eat in a day.

The recommended daily intake (RDI), which is another established value, represents the nutrient requirements for 97-98% of healthy individuals.

The recommended daily intake of protein is 46-63 grams for most adults, and up to 65 grams per day for women who are pregnant or breastfeeding.

How to calculate how much protein you need

Ultimately, either the DV or RDI for protein should theoretically meet the daily protein requirements for most adults, but depending on your activity levels, body size, and body composition goals, you may want to eat more protein per day.

Let’s look at how to calculate how much protein you need to eat in a day based on your body size and physical activity levels.

According to recommendations for general health set forth by The Academy of Nutrition and Dietetics, adults should aim to consume 0.8 grams of protein per kilogram of body weight per day, or 0.35 grams of protein per pound of body weight per day. These protein recommendations are the same as those set forth by the National Academy of Medicine, which are to consume a minimum of 0.8 grams of protein for every kilogram of body weight per day, or just over 7 grams of protein for every 20 pounds of body weight.

Using these recommendations,

• A 150-pound person would need about 55 grams of protein each day.
• A 180-pound person would need about 63 grams of protein each day.
• A 220-pound person would need about 80 grams of protein per day.
• A 250-pound person would need about 91 grams of protein per day.

The protein requirement for active individuals and athletes tends to be higher because protein is needed to repair and rebuild muscles after exercise, and it aids workout recovery. For this reason, the American College of Sports Medicine recommends that athletes consume a minimum of 1.2-2.0 grams of protein per kilogram of body weight per day.

For example, an athlete weighing 185 pounds (84 kg) should consume at least 101–168 grams of protein per day to meet his or her daily protein requirements. Since there are four calories per gram of protein, this range equates to 404-672 calories of protein.

Your own protein needs might vary based on your specific exercise routine, health, and goals, but most sports dietitians recommend that active adults should aim for a protein intake of 20%-35% of their daily caloric intake.

The table below shows how much protein you should eat per day based on the recommendations discussed. The first two columns denote body weight in pounds and kilograms, respectively. The third column lists the protein recommendations for the average adult based on the recommendations from the National Academy of Medicine and The Academy of Nutrition and Dietetics. The fourth and fifth columns show the protein recommendations for athletes set forth by the ACSM. The first column shows the lower end of the range, and the final column shows the upper end of the range.

Which foods are the best sources of protein?

Protein is easy to come by in a variety of foods. Most animal products like fish, poultry, meat, eggs, milk, yogurt, and cottage cheese are rich in protein. Of course, if you’re watching the waistline or are in the process of bulking up muscle mass, you’ll want to focus on leaner proteins like chicken breast and salmon. If you eat a plant-based diet, you’re not out of luck. Naturally, vegan foods like tofu, lentils, edamame, chickpeas, black beans, and quinoa are all wonderful sources of protein as well.

Of course, protein powders, protein bars, and protein shakes will help you get your fix, too, but whole-food sources are usually ideal.

Ultimately, it’s important to know how to calculate how much protein you need to eat per day to make sure you’re eating enough protein to support your workouts and overall health.