How Semaglutide Works — Mechanism Explained

Questions readers ask

Why is semaglutide injected only once a week?

Semaglutide has a half-life of about seven days, which allows a single weekly subcutaneous injection. The oral version, Rybelsus, instead relies on an absorption enhancer so that it can be taken as a daily tablet.

How does semaglutide reduce appetite?

By activating the GLP-1 receptor, semaglutide slows gastric emptying, which keeps you feeling full for longer, and reduces caloric intake. It also triggers glucose-dependent insulin secretion and suppresses glucagon, which is why it is used for type 2 diabetes as well as weight management.

Does semaglutide raise insulin even when blood sugar is normal?

The page describes semaglutide’s insulin effect as glucose-dependent, meaning GLP-1 receptor activation boosts insulin secretion in response to glucose rather than independently of it. It works alongside glucagon suppression to help regulate blood sugar.

How much weight loss has this mechanism produced in trials?

In the STEP 1 trial, semaglutide 2.4 mg once weekly produced a mean weight loss of 14.9% at 68 weeks using the treatment-policy estimand, in adults with overweight or obesity.