When most people think about protein in their body, they think of muscle. The truth is, protein does a whole lot more than just build muscle.
Protein is involved in nearly everything your body does. Everything from healing wounds to producing hormones, protein plays a role.
So if you've ever asked, "What does protein do in the body?" or "What are the functions of protein in the body?" you're in the right place.
I'll break it all down simply and clearly so you can go out and crush your goals.
In This Article:
• What Is Protein?
• What Does Protein Do in the Body?
• Best Sources of Protein
• How Much Protein Do You Need?
• Can You Eat Too Much Protein?
• Best Ways to Get More Protein
• Frequently Asked Questions about Protein Functions in the Body
• Final Thoughts
What Is Protein?
Protein is one of the three main nutrients your body needs. The other two are carbohydrates and fats. These 3 all fall under a category called macronutrients, which we need in large amounts every day.
Protein is made up of tiny building blocks called amino acids. You can think of amino acids in protein like beads on a string. They're strung together in different combinations to create different types of protein.
Now, when it comes to protein ... There are two main types:
Complete Proteins: These proteins contain all 9 essential amino acids, which are the amino acids your body can't make on its own. Some examples of complete proteins would be foods like meat, fish, eggs, and dairy sources like whey protein.
Incomplete Proteins: These are missing at least one or more of the essential amino acids. Most plant-based proteins fall into this group.
What Does Protein Do in the Body?
Understanding what protein does in the body goes way beyond muscle building. Protein plays a lot of important roles. Here's what protein does in the body, and why it matters:
1. Protein Builds and Repairs Muscle Tissue
When you work out, your muscles get little tears in them. Muscles are made mostly of protein, so that's what they need to repair themselves. This is why it's so important to get more protein, and this is especially true around your workouts (1).
This is probably the most well-known answer to "what does protein do in the body," but it's just the beginning!
2. Supports Healthy Skin, Hair, and Nails
Your skin, hair, and nails are mostly made of protein. Getting enough protein helps them grow stronger and stay healthy (2, 3). All tissues break down over time and need to be rebuilt. So if your hair, skin, and nails are important to you, make protein a priority.
3. Helps Form Enzymes for Digestion and Metabolism
Your body uses protein to make enzymes (4). These help us break down food and speed up processes in our bodies. This is another crucial aspect of what protein does in the body that most people don't realize!
4. Produces Important Hormones
Hormones like insulin, growth hormone, and even some brain chemicals are made from protein (5). Without them, our bodies can't send the right signals and function how we're supposed to.
5. Boosts the Immune System
Your immune system uses protein to create antibodies and many other immune cells (6). These are the little fighters that help protect you from getting sick. This immune function is a vital part of what protein does in the body for overall health!
6. Transports Nutrients Like Oxygen
Hemoglobin, a protein in red blood cells, carries oxygen from your lungs to the rest of your body (7). Other proteins move vitamins and nutrients around too. To make these proteins optimally, we need adequate protein intake.
7. Maintains pH Balance in the Body
Proteins help your body regulate its pH level (8). We need our pH tightly regulated so it doesn't become too acidic or too basic. That balance is crucial for staying healthy.
8. Promotes Satiety and Reduces Cravings
Protein makes you feel full longer than carbs or fat (9). It also can help reduce sugar cravings and make it easier to stay on track with your goals.
9. Helps Regulate Blood Sugar Levels
Eating protein with meals can slow down how fast sugar enters your bloodstream (10). This can help you avoid energy crashes throughout the day.
10. Provides Structural Support to Tissues
Protein builds the framework for tendons, ligaments, cartilage, and bones (11). Protein is not just in your muscles.
As you can see, the functions of protein in the body are incredibly diverse and essential for optimal health!
Best Sources of Protein
Here are some high-quality protein options to keep in your diet:
| Animal-Based Proteins | Plant-Based Proteins |
|---|---|
| Chicken / Beef | Lentils |
| Fish (like Salmon or Tuna) | Quinoa |
| Eggs | Chickpeas |
| Greek Yogurt | Tofu |
| Whey Protein Powder | Pea Protein & Rice Protein Powder Combo |
How Much Protein Do You Need?
The amount of protein you need every day differs from person to person. If you're going by the Recommended Dietary Allowance (RDA), it would be 0.8 g/kg bodyweight.
If you ask anyone in the fitness industry, though, pretty much everyone agrees this number is too low. This is because the RDA is set ONLY to prevent malnutrition. So that amount is the bare minimum.
It likely won't be enough to prevent muscle loss or help with your fitness goals. Studies have looked at this too, and found there are benefits to eating more protein than the RDA (12).
When it comes to fitness, I recommend a range between 1 gram of protein per pound of your goal body weight and your actual body weight. So if you're 180 pounds and want to lose 10 pounds, stay between 170-180 grams of protein per day.
If you go over that amount, it's completely fine too. I go over my protein goal all the time, and hit over 300 grams some days.
Can You Eat Too Much Protein?
Most healthy people don't need to worry. If your kidneys are working fine and you drink enough water, eating a high-protein diet is generally safe.
In fact, they studied this in men who regularly work out over the course of a year. They found that there were no harmful effects (13).
I don't think you'll find much benefit eating more than 1 gram of protein per pound of bodyweight. At least studies show it's safe to do so if you choose to.
Best Ways to Get More Protein
• Eat protein with every meal - chicken, beef, eggs, Greek yogurt, etc.
• Snack smarter - beef jerky/meat sticks, whey protein bars, cottage cheese
• Use a quality protein supplement - Whey protein powder, plant-based protein powder with at least two sources of protein (peas & rice, for example)
Frequently Asked Questions About What Protein Does in the Body
Q: What Does Protein Do in the Body for Muscle Building?
A: Protein provides the amino acids your muscles need to repair and grow after workouts. When you exercise, you create tiny tears in muscle fibers, and protein supplies the building blocks to repair them stronger than before. This is why protein is essential in the body for anyone trying to build or maintain muscle mass.
Q: What Are All the Functions of Protein in the Body?
A: Protein has 10 major functions in the body:
• Building/repairing muscle tissue
• Supporting skin/hair/nails
• Forming digestive enzymes
• Producing hormones
• Boosting immune function
• Transporting nutrients like oxygen
• Maintaining pH balance
• Promoting satiety
• Regulating blood sugar
• Providing structural support to tissues
These diverse functions of protein in the body show why it's so essential!
Q: Why Does the Body Need Protein for So Many Functions?
A: The body needs protein because amino acids are the building blocks for almost everything in your body. From muscles to hormones to enzymes, protein is required to create and maintain these vital structures. That's why what protein does in the body is so comprehensive ... it's literally the foundation of cellular function!
Q: How Does Protein Function in the Body for Weight Loss?
A: Protein helps with weight loss by increasing satiety (keeping you full longer). It can also help support metabolism through the thermic effect of food, preserving muscle mass during calorie restriction, and reducing cravings. These protein functions make it easier to stick to your diet and maintain results long-term.
Q: What Does Protein Do in the Body for Recovery?
A: Protein supports recovery by providing amino acids for muscle repair, reducing inflammation, supporting immune function, and helping rebuild damaged tissues. This is why protein is crucial for anyone who exercises regularly. It helps the body bounce back stronger from workouts.
Q: What Are the Most Important Functions of Protein in the Body?
A: The most critical functions of protein in the body are: muscle building and repair, hormone production (especially insulin), immune system support through antibody creation, and enzyme formation for digestion and metabolism. These core protein functions are essential for survival and optimal health.
Q: What Does Protein Do in the Body for Aging?
A: As we age, protein becomes even more important for maintaining muscle mass, bone density, skin elasticity, and immune function. Protein helps combat age-related muscle loss (sarcopenia), supports wound healing, and maintains the structural integrity of tissues throughout the body.
Q: How Much Protein Does the Body Need to Perform All These Functions?
A: To support all the functions of protein in the body, most active individuals need 1 gram per pound of goal body weight daily. This ensures adequate amino acids for muscle repair, hormone production, immune function, and all other protein functions while supporting fitness goals.
Q: What Happens If Protein Doesn’t Function Properly in the Body?
A: When protein function is impaired, you might experience: muscle weakness, fatigue, hair loss, slow wound healing, frequent infections, edema (swelling), and poor recovery from exercise. This shows how critical protein functions are for overall health and wellbeing.
Q: Can I Get Enough Protein to Support All Body Functions without Meat?
A: Yes! You can support all protein functions in the body with plant-based sources by combining proteins like rice and peas, or using complete plant proteins like quinoa. It takes more planning, but you can definitely meet all your body's protein function needs without animal products.
Final Thoughts
Protein isn't just for gym rats or bodybuilders. Understanding what protein does in the body shows us it's one of the most important nutrients.
Whether you're trying to lose fat, build muscle, or feel more energized ... getting enough protein should be a top priority. The diverse functions of protein in the body make it essential for every fitness goal and for your overall health.
Protein isn't all that's important if you want to build muscle or lose weight, though. You also have to pay attention to the amount of calories that you eat.
Eating more calories than you burn will help you gain weight. Eating fewer calories than you burn will help you lose weight.
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References:
(1) Cintineo HP, et al. Effects of Protein Supplementation on Performance and Recovery in Resistance and Endurance Training. Front Nutr. 2018;5:83.
(2) Guo EL, Katta R. Diet and hair loss: effects of nutrient deficiency and supplement use. Dermatol Pract Concept. 2017;7(1):1-10.
(3) National Research Council (US) Subcommittee on the Tenth Edition of the Recommended Dietary Allowances. Recommended Dietary Allowances: 10th Edition. National Academies Press (US). 1989.
(4) LaPelusa A, Kaushik R. Physiology, Proteins. StatPearls Publishing. 2022.
(5) Hoffman JR, et al. Effect of protein intake on strength, body composition and endocrine changes in strength/power athletes. J Int Soc Sports Nutr. 2006;3(2):12-18.
(6) Li P, et al. Amino acids and immune function. Br J Nutr. 2007;98(2):237-52.
(7) Rhodes CE, et al. Physiology, Oxygen Transport. StatPearls Publishing. 2022.
(8) Hopkins E, et al. Physiology, Acid Base Balance. StatPearls Publishing. 2022.
(9) Paddon-Jones D, et al. Protein, weight management, and satiety. Am J Clin Nutr. 2008;87(5):1558S-1561S.
(10) Luhovyy BL, Kathirvel P. Food proteins in the regulation of blood glucose control. Adv Food Nutr Res. 2022;102:181-231.
(11) McKee TJ, et al. Extracellular matrix composition of connective tissues: a systematic review and meta-analysis. Sci Rep. 2019;9(1):10542.
(12) Wolfe RR, et al. Optimizing Protein Intake in Adults: Interpretation and Application of the Recommended Dietary Allowance Compared with the Acceptable Macronutrient Distribution Range. Adv Nutr. 2017;8(2):266-275.
(13) Antonio J, et al. A High Protein Diet Has No Harmful Effects: A One-Year Crossover Study in Resistance-Trained Males. J Nutr Metab. 2016;2016:9104792.
