The implant is already a terrible idea, but making it wirelessly controllable would be even worse. How long until someone dies because some asshole hacked their implant and cranked up the metabolic rate?
You would make more money marketing it as a weight loss strategy. Turn it on until you reach your weight loss goal then turn it off. Repeat after every holiday season.
In the real world, there would be no reason not to be able to turn it off or down if you don’t have enough food. There has to be some way to interface with it, wireless or not, or else it can’t charge anything.
Seems the easiest way would be to just not charge your device. Once the battery is full, surely it can’t keep on burning energy. So, rather than going hungry, you just have to charge your phone with the mains. Not that big a deal.
If this was lower, more like 1500 calories, I think I could do it. You can live on 1500 calories, and I can probably easily get to 3000 calories if I just keep eating when I’m hungry. The problem of having enough food comes in, but that’s why I throw in the above.