What Is Protein and Why Does It Matter?

Protein is a macronutrient that your body needs in large amounts. It provides amino acids essential for muscle repair, immune function, hormone production, and more. Both animal-based and plant-based foods can supply dietary protein, though the quality and quantity may differ.

Research shows that adequate protein intake supports body composition, bone health, metabolic function, and overall well-being.

Different Types of Protein

Animal-Based Proteins

Animal proteins, such as meat, fish, dairy, and eggs, are considered complete proteins. They contain all nine essential amino acids that the body cannot produce on its own. These proteins are more digestible and effective at building and repairing muscle.

Plant-Based Proteins

Plant proteins, like lentils, nuts, and tofu, are typically incomplete, missing one or more essential amino acids. However, eating a variety of plant protein sources throughout the day can meet your amino acid needs. Recent studies show it's not necessary to combine them in the same meal.

Health Benefits of Protein

Supports Muscle and Bone Health

Protein is essential for muscle repair and growth. A high-protein diet, combined with resistance training, improves strength and recovery. Protein also supports bone density and reduces the risk of fractures and osteoporosis.

Supports Vital Body Functions

Protein contributes to immune response, neurotransmitter production, and skin, hair, and hormone health. Inadequate intake may impair immunity, mental clarity, and overall resilience.

Regulates Appetite and Blood Sugar

Protein slows digestion and helps maintain steady blood sugar levels. It also promotes satiety by stimulating the release of fullness hormones while reducing hunger hormones. This makes it beneficial for weight management and glucose control.

How Much Protein Do You Need?

The Recommended Dietary Allowance (RDA) for protein is 0.8 grams per kilogram of body weight. This is the minimum to prevent deficiency.

People who are physically active or trying to build muscle generally need 1.2 to 2.0 grams per kilogram daily. Those aiming for fat loss while maintaining muscle may need up to 2.3–3.1 grams per kilogram. Needs also increase during pregnancy, recovery, or illness.

Good Sources of Protein

Animal-Based Sources

  • Chicken breast: 31 g per small piece

  • Whey protein: 25 g per ounce

  • Cottage cheese: 23.5 g per cup

  • Shrimp: 20.4 g per 3-ounce serving

  • Tuna: 20.1 g per 3-ounce serving

  • Greek yogurt: 19.9 g per 7-ounce serving

  • Salmon (canned): 19.6 g per 3-ounce serving

  • Eggs: 6.3 g per large egg

Plant-Based Sources

  • Pea protein: 24 g per ounce

  • Tempeh: 19.9 g per 100 grams

  • Edamame: 18.5 g per cup

  • Lentils: 17.9 g per cup

  • Hemp seeds: 9.5 g per ounce

  • Tofu: 8.7 g per 3-ounce serving

  • Peanuts: 7.4 g per ounce

  • Chickpeas: 14.5 g per cup

Supplements

Protein powders are a convenient option, with both animal-based (whey, casein, collagen) and plant-based (pea, soy, hemp) varieties available. Most provide 20 to 25 grams of protein per serving. Choose third-party tested products for safety and quality.

Risks and Side Effects of High Protein Intake

For most healthy individuals, high-protein diets are safe, even at intakes above 3 grams per kilogram of body weight. However, excessive consumption of processed or red meats has been linked to increased risk of heart disease and certain cancers.

People with existing kidney conditions should consult a healthcare provider before increasing protein intake significantly.

Protein Deficiency

Protein deficiency is rare in developed countries but more common in regions with food insecurity. Severe deficiency can lead to kwashiorkor, especially in malnourished children. Older adults and people with chronic illness may also be at risk of inadequate protein intake.

A Quick Recap

Protein is essential for muscle growth, immune function, hormone production, and cognitive health. Meeting your daily protein needs through a mix of animal and plant-based foods supports a strong, healthy body.

If you're unsure how much protein you need, a registered dietitian can help create a plan based on your lifestyle and goals.