A plain-language, continually updated guide from Dr. Matt Chalmers’ clinical reference on hormones and peptides.
Glucagon is a hormone produced by the pancreas that works opposite insulin — raising blood glucose by triggering the liver to release stored sugar. It’s directly relevant to some of the newest developments in metabolic medicine, since it’s the third receptor activated by triple-agonist peptide therapies like Retatrutide (alongside GLP-1 and GIP).
Beyond its emergency role, glucagon receptor activation has a genuinely distinct effect that neither GLP-1 nor GIP produce on their own: it increases hepatic fat oxidation, promotes ketogenesis, and directly raises resting metabolic rate — meaning it actually helps your body burn more energy at rest, not just eat less. It’s also the most potent pharmacological signal for fat mobilization (lipolysis) of any pathway discussed in our metabolic reference material, and it activates brown fat tissue to burn calories as heat. This is exactly why the addition of glucagon-receptor activity in newer compounds like Retatrutide is considered such a meaningful step forward compared to GLP-1-only or GLP-1/GIP-only therapies.
Glucagon is FDA-approved as a prescription therapy, most commonly for emergency treatment of severe hypoglycemia. Triple-agonist compounds that activate the glucagon receptor for metabolic purposes (like Retatrutide) remain investigational — see that page for current regulatory status.
Glucagon raises blood glucose by triggering the liver to release stored glucose — the opposite action of insulin. It’s FDA-approved as a prescription therapy, most commonly for emergency treatment of severe hypoglycemia. Beyond that emergency role, its receptor is also a documented driver of increased resting metabolic rate and fat mobilization, which is why it’s a component of newer investigational metabolic therapies.
Its receptor is a target of newer triple-agonist compounds like Retatrutide (see that page), where glucagon receptor activation is studied for its role in raising resting metabolic rate and driving fat mobilization — a distinct contribution that GLP-1 and GIP activity alone don’t provide.
See how glucagon receptor activity factors into Retatrutide, our featured triple-agonist compound. Also related: Insulin.
This page draws on The Pillars Path: A Root-Cause Guide to Hormones, Peptides, and Metabolic Health by Dr. Matt Chalmers — Pillars of Wellness’ clinical reference on hormone and peptide therapy.
