Peptides 💫 What Are Peptides? Peptides are short chains of amino acids  that act as the building blocks of proteins. Your body naturally produces them, and they’re involved in countless physiological functions — from hormone regulation  to cell repair . A well-known example is insulin , a peptide hormone crucial for regulating blood sugar levels. Today, scientists are also creating synthetic peptides , which are transforming medicine, cosmetics, and even sports performance.