1.   Injecting the hormone risks side effects such as liver problems, blood thickening, acne and breast development.

2.   It is fully implanted, and instead of injecting insulin under the skin, it injects the hormone directly into the peritoneal cavity in the abdomen.

3.   This device, placed against the thigh, automatically injects the hormone, which can counter a serious allergic reaction.

4.   Injecting the hormone in rodents makes them eat right away, but ghrelin has not been proven to stimulate appetite in people.