OniGumo wrote
I can see it all now, It could be called the FF mystical diet plan!
*slogan* Tired of your fat belly, wishing to be thinner? Sign up for the FF mystical plan and donate your poundage to a frustrated gainer! The plan is simple, just sign the magic contract and eat to your hearts content, your body will keep only what it needs to survive, the rest will go to the lucky gainer!
Oooh, I've always loved this idea, like a Voodoo stomach, had an idea for a story where a girl loves to eat but doesn't like being fat, so they do the voodoo magic and she can stuff herself silly while her bf gains all the weight, which of course she adores.