If you’re looking to build muscle and strength, you probably already know the importance of a protein-packed diet paired with a solid strength-training routine. But even when you’ve got that dialed in, you might still be looking for ways to get an edge, which is why performance-enhancing drugs have always been part of the conversation. But in the last few years, there’s been a new player in the mix—peptides, and everyone seems to be talking about them.

Putting two or more together, something people call “peptide stacking,” is said to promote protein synthesis and muscle repair, leading to increased muscle mass and strength. Since peptides are, in fact, short chains of amino acids (the building blocks of protein), it’s easy to see why workout enthusiasts are trying this trend.

To separate fact from flex, we talked to experts to uncover the truth: Is peptide stacking a legit strength hack, or just the latest fitness fad?

This article appears in the Men’s Journal Fitness Special, an Apple News+ exclusive. Read the full story HERE.