Ghrelin is a hormone secreted by the stomach that induces appetite. Studies looking to see if ghrelin is affected by gastric bypass are very inconsistent. Based on currently available information, no one can conclude that ghrelin is involved in the gastric bypass effect on eating. The exact mechanisms by which gastric bypass works remain unknown.

There is research investigating ghrelin and many other substances as potential medical treatments for obesity. Unfortunately, none appear very promising at the current time.

Drug development for obesity treatment wasn't yet successful. Eating is a basic, fundamental behavior, absolutely required for survival. Consequently, animals have evolved multiple redundant mechanisms to ensure that they seek and consume food. When a drug blocks one pathway, there always seems to be another that crops up to drive eating behaviors. Of the approximately 200 drugs being developed for obesity treatment, all appear to have relatively moderate, short-term weight-loss effects.