A professor at the University of Wisconsin has developed a device that can emit the same electric signal as the one that comes from your stomach when you ate.
The device is put in your stomach without batteries.

A signal comes from the device at the timing when your stomach moves.
The signal go to your nerve.
Your brain misunderstand you are full now. (Gigazine)

It’s tough to put the device in my stomach.
I am happy if it is able to put on my neck.