Semaglutide

Tirzepatide is a single peptide that activates two receptors at once: GIP and GLP-1, the two main incretin hormones your gut releases after eating. It is FDA-approved as Mounjaro for type 2 diabetes and as Zepbound for chronic weight management and obstructive sleep apnea, and it has produced the largest weight-loss numbers of any approved drug to date. Like semaglutide, this is a heavily trialed, fully approved medicine, not a gray-market research compound.

Retatrutide is the heavy hitter of the new weight-loss drugs: a once-weekly injectable peptide that hits three receptors at once - GIP, GLP-1, and glucagon - earning it the nickname triple-G agonist. In a phase 2 trial it produced some of the largest weight loss ever recorded for a drug, up to roughly 24 percent of body weight at the top dose. It is investigational, made by Eli Lilly, and not yet FDA approved as of 2026.

AOD-9604 is a synthetic fragment of human growth hormone, copying just the last 15 amino acids of the hormone (residues 176 to 191) plus a tyrosine cap. The idea was to keep the fat-burning end of growth hormone while leaving out the part that raises IGF-1 or messes with blood sugar. It was developed by Metabolic Pharmaceuticals in Australia and tested as an anti-obesity drug, but it is not approved by the FDA or any major regulator, and development stopped after it missed its weight-loss targets.

Orforglipron is Eli Lilly's oral, once-daily GLP-1 receptor agonist, and the headline is that it is a small molecule, not a peptide, so it survives the gut and can be taken as a plain pill with no food or water restrictions. It is being developed for type 2 diabetes and obesity and has completed multiple successful Phase 3 trials. As of mid-2026 it is filed for regulatory review but not yet approved.

Liraglutide is a once-daily injectable GLP-1 receptor agonist, a synthetic peptide that shares about 97% of its sequence with the natural gut hormone GLP-1 but is engineered with a fatty acid chain so it survives in the body far longer. It is FDA-approved as Victoza for type 2 diabetes (2010) and as Saxenda for chronic weight management (2014), and is one of the most studied drugs in its class. As of 2024 a generic version is also FDA-approved.

Dulaglutide (brand name Trulicity) is a once-weekly injectable GLP-1 receptor agonist made by fusing a modified GLP-1 peptide to a fragment of a human antibody, which is what lets it last a full week between shots. It is FDA-approved for type 2 diabetes and, notably, to reduce cardiovascular risk in adults with diabetes. The once-weekly dosing made it a major convenience step up from earlier daily and twice-daily agents.