The trouble with Leptin is that when its out of whack we stop producing brown fat. So no fat between the organs where it should be while the body continues to go nuts trying to have some fat storage.
This in some people, especially together with Colloids of Mercury from Chlor Alkali plants, can make them gain lots of unlooseable weight.
Worse for those that gain massive amount of weight while pregnant since the body demands the internal fat during pregnancy. But these days with HCG everywhere this could be said for all of us..