Human peptides are short chains of amino acids linked together that act as vital chemical messengers throughout the body. They are essentially smaller, simpler versions of proteins. While proteins are typically made of complex chains of over 100 amino acids, peptides are much shorter, usually containing between 2 and 100 amino acids.
Amino acids are the building blocks of proteins; longer chains usually fold into proteins, while shorter chains are called peptides. Peptides also act as signals in the body—for example, some hormones are peptides.
Scientists have cataloged around 7,000 naturally occurring peptides in the human body. Because they are small and water-soluble, they can move quickly to bind with specific cell receptors, triggering a domino effect of essential biological commands.
For muscle, peptides from food protein are broken down and absorbed, supplying amino acids that the body can use to build and repair muscle proteins. Resistance exercise signals the muscles to adapt and grow; amino acids provide some of the raw materials for that process.
Food protein
↓ digestion
Amino acids + small peptides
↓ absorbed and carried in blood
Muscle uses amino acids to build and repair proteins
↑
Resistance training signals muscle to adapt and grow
So peptides are part of the body’s protein supply, but eating peptides alone doesn’t make muscles grow: growth depends on training, adequate nutrition, and recovery.