The hormone you were told to fear is now in the strongest compounds.

Glucagon has a bad reputation. It raises blood sugar, the opposite of what a metabolic drug should want. So it surprises people that the most powerful investigational compound deliberately activates it. The reason is the second face of glucagon the reputation leaves out.

Glucagon comes from the alpha cells of the pancreas. Its classic job is to raise blood glucose when you have not eaten. But it also increases energy expenditure, promotes the breakdown of stored fat, and can blunt appetite. Used in a controlled way, alongside hormones that handle the blood-sugar side, it becomes a lever for spending energy rather than only eating less. GLP-1 and GIP work largely by reducing intake. Glucagon adds output.

This is the logic behind retatrutide, an investigational triple agonist combining GIP, GLP-1, and glucagon. In its phase 2 trial, the reported weight loss at the highest dose reached roughly a quarter of body weight, among the largest figures published for this class. Two cautions belong in the same breath. Retatrutide is investigational, not FDA approved, and the glucagon arm must be balanced carefully against its glucose-raising effect.

That completes the set. One hormone, two, three. Semaglutide pulls one lever, tirzepatide two, retatrutide three. Learn the three hormones and the entire metabolic drug race resolves into a single clear pattern.