If semaglutide works universally, or nearly so—and early studies are very promising—then that might be a strong hint as to what is causing the obesity epidemic.
Relatedly, this seems to be the distribution of weight changes on 15 mg of tirzepatide + lifestyle interventions, compared to lifestyle interventions alone (over 72 weeks, I think):
Relatedly, this seems to be the distribution of weight changes on 15 mg of tirzepatide + lifestyle interventions, compared to lifestyle interventions alone (over 72 weeks, I think):