What Does Protein Do For Your Body?

It’s hard to say if it was the cottage cheese wrap or the chicken pizza that brought protein back into the spotlight, but either way, we’re not mad about it. And, apparently you aren’t either! As of July 2024, more than 14 million cups of cottage cheese have been logged by MyFitnessPal users around the world. 

Understanding why protein is so essential can help you make more informed food choices. In this deep dive, we’ll cover all the ways protein impacts your body. You’ll learn how to decide what your personal protein goal should be and how to achieve it through a balanced diet. 

What is Protein and Why is It Important? 

Aside from water (which makes up 55-60% of the body), protein takes up the second most space, accounting for 18 to 19% of your body weight (1, 2). Protein is one of the body’s most important nutrients, present within every cell and working nonstop to keep metabolic health, immune function, bone health, and of course, lean muscle tissue at its prime (3). 

The main function of protein is to support the structure, function, and regulation of the body’s tissues and organs (3). To say proteins are kind of a big deal would be an understatement. 

Let’s explore what proteins actually are.

Protein as a Macronutrient

Protein, alongside carbohydrates and dietary fats, is a macronutrient (4). Macronutrients are essential nutrients that the body requires in large amounts to function effectively (4). Each macronutrient plays a vital role in maintaining health (4). Protein has about 4 calories per 1 gram, meaning 20 grams of protein adds up to about 80 calories (4). 

Protein functions in the body not only to build and repair tissues (especially when it comes to recovery after a workout), but it also plays an important role in hormone, immune, and metabolic health (5). 

Amino Acids: The Building Blocks of Protein

Proteins are made up of a combination of 20 units called amino acids (5). Amino acids are tiny but mighty components of protein that help protein carry out the necessary functions in the body. Simply put, amino acids are often referred to as the building blocks of protein. The two major types of amino acids are essential and non-essential. 

The body is a marvelous thing! It can actually create 11 of the amino acids needed for protein to function throughout the body whether or not we get them from food (5). As a group, they’re known as the non-essential amino acids.

Essential amino acids are those that our bodies can’t produce on its own; we need to get them from the foods we eat or a supplement (5). There are 9 essential amino acids (5). 

There’s no need to get caught up in exactly which amino acids are in each protein-rich meal, but you’ll want to get protein from all different protein sources (beans, tofu, lean meats, supplements). That will ensure you get  all 20 amino acids over the course of a day.

How Protein Supports Muscle Growth and Repair 

One of the best known functions of protein is its role in exercise recovery. Let’s explore how protein helps muscles recover from a workout, and just what amount you should be aiming for. 

Protein’s Role in Muscle Synthesis

Every time you workout, your body is under stress. This kind of stress is actually a good thing though. For instance, consider a strength training workout or recovery after an endurance event. Each bicep curl or stride in a marathon tears your muscle a little bit. 

Protein’s amino acids help repair the torn muscle tissue, resulting in the formation of new, stronger muscles (6). If you want to build or maintain muscle, you need to make sure you eat enough protein (7).

Protein for Recovery After Exercise

For optimal muscle growth and maintenance, sports authorities recommend eating  0.25 grams of protein per kilogram body weight immediately after exercise, which is about 20 to 40 grams of protein (7). 

Simple protein-rich foods can help you optimize protein here. For example, a 150-pound woman needs about 17 grams of protein, which can easily be achieved through 1-cup of Greek yogurt or an egg omelet made with 2 large whole eggs and 2 large egg whites (8, 9, 10).   

Eating protein throughout the day is a good idea, however the amount you need right after your workout is dependent on a few things, like your age, fitness level, exercise duration and frequency, and regular nutrition routine (7, 11).

Don’t worry about getting the timing and number of grams of protein exactly right. Just try to eat something protein rich within the first 60 minutes following your workout. You’ll reap the benefits of proteins’ ability to help build and repair muscle (7). 

Whole food protein sources, like Greek yogurt, chocolate milk, and even a handful of nuts are the ideal way to meet your protein needs during this recovery period. But these aren’t as convenient as a quick protein bar or shake, which are also fine protein options if you’re in a pinch. 

Checkout the MyFitnessPal list of the top 9 protein bars dietitians recommend as well as the best protein powders to consider adding to your routine. 

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About the experts

Elizabeth Shaw, MS, RDN, CPT is a nutrition expert, four-time cookbook author and early nutrition pioneer in the field of fertility nutrition. She is the president and owner of the USA-based nutrition communications and consulting firm Shaw Simple Swaps.

Stephanie Tarnacki, RD is a Food Data Curator at MyFitnessPal. She received her Bachelors in Dietetics from University of Northern Colorado and completed her Dietetic Internship at Montana State University.

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Protein’s Impact on Metabolism and Weight Management 

Melissa Jaeger, LD, RD, head of nutrition at MyFitnessPal, shares that protein’s impact on full body health extend beyond building muscle at the gym, writing, “Our body uses protein for a variety of internal functions that you and I may not think about day-to-day but are important for our overall health and wellbeing (12).” 

One such under-the-radar function: metabolism. 

Protein foods need to be digested. Digestion in and of itself burns energy, which is called the thermic effect of food (TEF) . Protein requires more energy than other macronutrients to break down for use in the body. (12)

Essentially, you burn more calories eating protein-based foods than carbohydrates or fats, giving you a slight metabolic boost when you opt for protein-rich nutrition sources (12). Eating a high-protein diet in combination with an active lifestyle may further support your metabolism and health goals.

Fun fact: On average, MyFitnessPal members in the United States who want to lose weight consume 24% of their calories from protein.  Remember, 1 gram of protein contains 4 calories, so a member with a 1400-calorie daily calorie goal eats, on average, around 83 grams of protein per day.

Protein for Satiety and Weight Loss

Protein foods also increase satiety, or how full you feel after eating  (12). This can bode well for someone with a weight loss goal since protein may help appetite control and minimize overeating, essentially keeping you fuller for longer (12).

In fact, research shows that gut hormones are involved in satiety, helping suppress appetite (12). These hormones help signal to your body that you’ve satisfied your hunger after consuming a high protein meal (12).

How Protein Supports Immune Function 

Is it starting to feel like there’s nothing protein can’t do? Believe us, we’re pretty impressed too. Let’s take a closer look at protein’s role in immune health. 

Protein and Antibody Production

Proteins play a critical role in immune health. In fact, amino acids actually help make up immune proteins that protect the body from infections (13). Antibodies help capture foreign invaders, like viruses and bacteria, that can wreak havoc on the body (3). Think of them as your own personal bodyguards! It’s important to include a variety of protein sources in the diet to support a healthy immune system and keep your internal security system healthy. 

Protein Deficiency and Immune Health

When dietary protein is lacking, immune health can suffer. Protein deficiency, Jaeger notes, is referred to as protein energy malnutrition (PEM), and occurs when both calorie and protein needs are not met in sufficient amounts of an individual’s requirement (14). We usually see this in underdeveloped countries.

While PEM is an extreme condition, active individuals may still not meet their personal protein needs. We wouldn’t classify this as PEM, but still, a protein deficient diet (15). For instance, if an active individual doesn’t meet their individual protein needs, they may find themselves feeling worn out, recovering slower from illness, and even sick more often (15). 

Protein and Bone Health

Protecting bone health is extremely important, especially with age. Protein plays an important role, alongside nutrients like calcium, vitamin D, magnesium, phosphorus, and zinc, in bone development (16).  

These nutrients not only are essential during important life stages when bone growth and development are at their prime, like infancy and puberty, but also as we get older and bone density becomes a concern. 

Essentially, bone density, or bone mass as it’s also called, is the rate at which the body breaks down old bone and replaces it with new bone (17). As we age, this process slows down, and protecting bone density is essential. Including a variety filled diet, filled with protein rich foods and these other bone health nutrients will help to preserve your bone health long term (16). 

Osteoporosis Prevention

Osteoporosis is a serious condition that affects bone health, resulting in a decrease in bone density and bone strength, making you more susceptible to bone breaks (18). While it’s important throughout life to focus on a protein-rich diet to support lifelong bone health, older adults especially need to focus on protein to support their bones (19). 

How Much Protein Does Your Body Need? 

Defining how much protein your body needs is highly individualized. You need to consider your age and weight, activity level, fitness level, and health goals. 

General Daily Recommendations

Protein intake recommendations are based on the Recommended Dietary Allowance, or RDA for short, that covers the essential needs of a healthy person to prevent lean muscle loss (20). 

The RDA for protein is 0.8 grams of protein per kilogram of body weight (or about 0.36 grams per pound) (20). 

These ranges don’t factor in exercise or specific weight goals, so if you workout, you should aim for closer to 1.4 to 2 grams per kilogram of body weight (or roughly 0.6-1 gram/pound) (7). 

For someone weighing approximately 150 pounds, this would equate to a protein intake range of roughly 95 to 136 grams of protein per day. 

How to Calculate Your Protein Needs

Calculating your personal protein needs does require a little math, but we promise, if this isn’t your strong suit, head over to the MyFitnessPal Macro Calculator and let us do the math for you. 

If you’re up for the challenge, it’s best to start by calculating a protein range. First, consider your personal health goals, such as muscle gains, recovery, or weight loss, and your activity level. Once you’ve addressed these, follow these simple steps. 

1. Multiply your weight (in pounds) by 0.36 grams to find your base protein needs based on the RDA (21).
   1. 150-pounds x 0.36 g/lb = 54 grams protein per day
2. Next, depending on your activity level, you’ll multiply your weight in pounds by your protein needs.
   1. To get this protein range, use what sports nutritionists advise, which is that 0.6 to 1.0 grams/pound (7).
      1. 150 x 0.6 to 1.0 = 90 – 150 gm/kg

Working with a dietitian is the best way to figure out your true protein needs. 

FAQs

The Bottom Line: The Importance of Protein for Overall Health 

The benefits of protein for the body are endless. From its pivotal role in building and maintaining lean muscle tissue, to keeping our metabolism running at its prime, to supporting immune health, and ensuring bones remain strong throughout the lifetime, protein’s impact is seen throughout the body. 

Meeting your daily protein needs to ensure these daily functions are carried out has never been so important. Use the Macro Calculator to figure out your personal protein needs based on your individual activity habits.

Then, make it a habit to choose protein-rich foods at meals and snacks. Better yet, build your plate around your personal protein pick, volumizing the remainder of your meal with other nutritious choices, like whole grains, fruits and vegetables, and a source of healthy fats. 

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