How each generation adds a new signal
What glucagon receptor activation adds
Glucagon is usually associated with raising blood sugar. It is the hormone that tells the liver to release glucose when blood sugar drops. But glucagon receptors sit in many other tissues, and switching those on has effects beyond blood sugar:
Increases energy expenditure
The glucagon signal raises the calories the body burns at rest. That is a thermogenic effect, and it is not seen with GLP-1 or dual agonists.
Reduces appetite
Glucagon also suppresses appetite, through receptors in the brain and spinal cord. That adds to the GLP-1 and GIP effects.
Breaks down fat
Stimulates fat breakdown (lipolysis) in the liver and in fat tissue. That speeds up fat loss beyond eating less alone.
Reduces liver fat
Blocks the liver from making new fat, and pushes it to burn fat instead. That matters 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.
GLP-1
Appetite reduction + gut slowing + insulin secretion
GIP
Boosts the appetite effect + fat metabolism + tolerability
Glucagon
Increased energy expenditure + fat breakdown + liver fat reduction
Investigational — not yet approved
Retatrutide (the leading triple agonist) is in Phase 3 trials. In one Phase 3 trial in people with obesity and knee osteoarthritis, participants lost an average of 28.7% of body weight at 68 weeks. That was 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
Common questions
Written and maintained by one person · Built with agentic AI tools · Every number checked against the cited trial · Not medical advice
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