close Peptides can be useful, but some people may be moving too fast, expert warns New York fitness trainer and gym owner Kenny Santucci discusses concerns about unverified peptide products for muscle building, saying consumers should work with physicians. NEW You can now listen to Fox News articles! As GLP-1 weight-loss medications gain traction, the peptide market is experiencing a surge in interest. A variety of peptides — commonly marketed for weight loss, muscle building, injury recovery