Therapeutic peptides are short chains of amino acids used to treat metabolic and endocrine conditions such as obesity and type 2 diabetes. While several peptide drugs have undergone rigorous approval processes that evaluate both safety and efficacy, novel, unapproved compounds have emerged and are rapidly expanding into preventive medicine and performance enhancement. Our objective is to present the effects, clinical applications, safety profiles, and regulatory status of prominent peptides used to treat several conditions. We reviewed 106 articles, prioritizing systematic reviews, meta-analyses, and randomized controlled trials in the PubMed, ScienceDirect, and SciELO databases. Our results suggest that therapeutic peptides are a promising tool for treating type 2 diabetes and obesity, for skin rejuvenation, and as hormone analogs for specific diseases and conditions. Although these are strategic and innovative options that can improve health, performance, and longevity, further studies are needed before most new peptides can be used safely in humans.