How Triple Agonists Work
Triple agonists add a glucagon signal on top of GLP-1 and GIP — tackling obesity from three angles. The key differentiator is the glucagon component: it increases energy expenditure, meaning the body burns more calories at rest, on top of reduced appetite.
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How each generation adds a new signal
*Phase 3 trial data — retatrutide not yet approved. Results may change.
What glucagon receptor activation adds
Glucagon is typically associated with raising blood sugar — it is the hormone that signals the liver to release glucose when blood sugar drops. But glucagon receptors exist in many other tissues, and activating them has effects beyond blood sugar:
- Increases energy expenditureGlucagon receptor activation raises the amount of calories the body burns at rest — a thermogenic effect not seen with GLP-1 or dual agonists.
- Reduces appetiteGlucagon also suppresses appetite via central nervous system receptors, adding to GLP-1 and GIP effects.
- Breaks down fatStimulates lipolysis (fat breakdown) in both liver and adipose tissue — accelerating fat loss beyond caloric restriction alone.
- Reduces liver fatInhibits de novo lipogenesis (new fat production in the liver) and stimulates fatty acid oxidation — important for fatty liver disease.
How the three signals combine
Plain English:
Triple agonists work on three appetite and metabolism signals at once. On top of the appetite suppression of GLP-1/GIP drugs, the added glucagon signal tells the body to burn more energy and break down fat more efficiently. This may explain why early trial results show even greater weight loss than dual agonists.
Investigational — not yet approved
Retatrutide (the leading triple agonist) is in Phase 3 trials. In one Phase 3 trial in participants with obesity and knee osteoarthritis, an average of 28.7% body weight was lost at 68 weeks — approximately 71 lbs on average. FDA approval is estimated 2027, subject to full trial results and regulatory review. These results are from a single Phase 3 trial and are subject to change. Source ↗
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Last reviewed: April 2026