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What Is Protein?

Protein is one of a complex group of molecules that do all kinds of jobs in your body. They make up your hair, nails, bones, and muscles. Protein gives tissues and organs their shape and also helps them work the way they should. In short, protein is one of the building blocks that make you into who you are.

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Emergency Energy

Protein isn’t your body’s first -- or even second -- choice for getting energy. That role is reserved for carbohydrates and fats. But when you’re running low on calories, or if you’re a serious athlete, thank protein for keeping you going past the point of normal energy stores. 

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Muscle Builder

You need protein to keep up the size and shape of your muscles. As you lose weight, protein prevents you from losing muscle at the same time. If you lift weights for strength, protein is the key to building more muscle. 

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Bone Strengthener

Studies show that getting the right amount of protein in your diet improves your bone health. It lowers your chance of osteoporosis (bone loss) by helping you hold on to your bone density, and it helps prevent breaks as you age, too.

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Boosts Your Immune System

Proteins are made of amino acids. These compounds help turn key players in your immune system -- T cells, B cells, and antibodies -- into germ fighters that spot and kill harmful cells that enter your body before they can start an infection.

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Cuts Cravings

Cravings are different than a true need for food. They come from your brain, not your stomach. Research shows that getting more protein can help curb these cravings, even late-night fridge raids.

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Burns Fat

A high enough level of protein in your diet boosts your metabolism (the rate at which your body uses calories). This means you burn more calories a day -- even at rest -- than you would on a lower-protein diet.

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Heart Helper

Studies on protein, specifically protein from plants, show that it can help lower blood pressure. It can also decrease your LDL or bad cholesterol levels, which lowers your risk of heart disease.

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Heals Injuries

There’s a reason protein is called the building block of your body’s tissues and organs. It powers faster wound repair by reducing inflammation and creating new tissue at the site of the injury.

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Moves Nutrients

If you think of your blood stream as a canal, proteins are the cargo ships that carry vitamins, minerals, sugars, cholesterol, and oxygen through it and into cells and tissues that need them to work. Some proteins even store certain nutrients, like iron, so you have a backup supply when you need it.

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Can You Get Too Much Protein?

A high-protein diet has clear benefits, but can too much harm your health? Yes, and the cost could be a higher risk of cancer, higher cholesterol, kidney stones, weight gain, and constipation. But many of these potential effects depend on the type of protein you’re getting and your overall diet. Ask your doctor or nutritionist what’s best for you.

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What Are the Best Ways to Get It?

Protein comes in lots of different forms. Reach for healthy, low-fat sources. Steer clear of saturated fats and highly processed options. Try to eat it throughout the day instead of cramming it into one meal. Keep up your fruit and veggie portions to get plenty of vitamins, minerals, and fiber.

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Sources | Medically Reviewed on 09/05/2021 Reviewed by Carol DerSarkissian, MD on September 05, 2021


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Genetics Home Reference: “What are proteins and what do they do?”

Skeletal Muscle: “The beneficial role of proteolysis in skeletal muscle growth and stress adaptation.”

The FEBS Journal: “Mechanisms regulating skeletal muscle growth and atrophy.”

Sports Medicine: “A brief review of critical processes in exercise-induced muscular hypertrophy.”

Journal of the American College of Nutrition: Dietary protein: an essential nutrient for bone health.”

Pharmacology, Biochemistry, and Behavior: “Food Craving and Food ‘Addiction’: A Critical Review of the Evidence From a Biopsychosocial Perspective.”

Obesity: “The effects of consuming frequent, higher protein meals on appetite and satiety during weight loss in overweight/obese men.”

The British Journal of Nutrition: “Presence or absence of carbohydrates and the proportion of fat in a high-protein diet affect appetite suppression but not energy expenditure in normal-weight human subjects fed in energy balance,” “Amino acids and immune function.”

PLoS One: “Dietary protein and blood pressure: a systematic review.”

JAMA: “Effects of Protein, Monounsaturated Fat, and Carbohydrate Intake on Blood Pressure and Serum Lipids.”

British Journal of Nursing: “The importance of patients' nutritional status in wound healing.”

Journal of Nutritional Science and Vitaminology: “Mg, Zn and Cu Transport Proteins: A Brief Overview from Physiological and Molecular Perspectives.”

Current Opinion in Lipidology: “Intestinal cholesterol transport proteins: an update and beyond.”

Antioxidants & Redox Signaling: “Intracellular Iron Transport and Storage: From Molecular Mechanisms to Health Implications.”

Harvard Health: “When it comes to protein, how much is too much?”

Reviewed by Carol DerSarkissian, MD on September 05, 2021

This tool does not provide medical advice. See additional information.

THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional medical advice, diagnosis or treatment and should not be relied on to make decisions about your health. Never ignore professional medical advice in seeking treatment because of something you have read on the WebMD Site. If you think you may have a medical emergency, immediately call your doctor or dial 911.