"When leptin failed, he tried a different gut hormone, ghrelin, whose effects were the opposite of leptin’s. The more ghrelin an animal had, the more it would eat. Perhaps a drug that blocked ghrelin would make people lose weight.
“Again, it wasn’t that simple,” said Dr. Tschöp, who left Lilly in 2002."
https://www.nytimes.com/2023/08/17/health/weight-loss-drugs-obesity-ozempic-wegovy.html
I discussed the origin of these new diabetes and weight loss drugs with Matthias, you can listen to "Obesity is a Brain Disease" scrolling down at the link below.