Protein: What It Does & Why It Matters

What is protein?

Protein is one of the main nutrients in food. It's made of smaller building blocks called amino acids. Your body breaks the protein you eat down into amino acids, then uses them to build the proteins it needs.

Some amino acids your body can make; others (the "essential" ones) have to come from food.

Why the body uses protein

• Building and repairing tissues
• Muscle tissue
• Enzymes that help chemical reactions happen
• Some hormones and signaling molecules
• Parts of the immune system
• Structural tissues like skin, hair, and connective tissue
• Transporting substances around the body

Protein & training

Resistance training creates the stimulus. Dietary protein provides amino acids your body uses for tissue remodeling and adaptation.

Eating protein on its own doesn't create muscle. Training gives the signal; protein is part of what your body uses to respond.

Protein sources

Preferences, dietary pattern, access, budget, and convenience all matter. The best sources for you are ones you'll actually buy and eat.

Plant vs. animal protein

Animal proteins generally contain all essential amino acids in a single food. Many plant foods contain lower amounts of one or more, which is why variety across the day is useful for people eating mostly plants. Soy is a plant option with a fairly complete profile.

Both can support a healthy diet and training. Neither is morally better. It comes down to your preferences, values, and needs.

You don't need to eat the same three "fitness foods"

Meeting your nutrition needs doesn't require living on chicken breast, rice, and Greek yogurt. There are dozens of protein-containing foods across every section of the grocery store.