"Some people can’t tolerate the side effects of the drugs and have to stop taking them. Others simply don’t respond. For some, the strength of the dose, or length of the treatment, does not seem to make a difference. Appetites might remain robust; the “food chatter” in the brain may stay noisy. Together, both groups of less successful GLP-1 users account for a not-insignificant share of patients on these drugs—potentially up to a third."

https://www.theatlantic.com/health/archive/2024/02/ozempic-not-working-weight-loss/677411/