i haven't ever heard this and i do know that they use coffee in some skincare recipes. if i remember correctly, caffeine is supposed to give a tightening effect when used topically. in guess ingesting it is another thing all together!
But there is something you all don't know about coffee. Applied topically, Coffee grounds are very beneficial to the skin.::shrugs::...I guess even coffee can be ambiguous.
Probably because coffee will dehydrate you. Caffeine is a diuretic and so you need to drink extra water when you have coffee to make up for the water loss, sort of like when you drink too much alcohol your whole body feels dried out too.