Have you lost weight just fine without any dieting? Without hunger? Anyone can lose weight by being hungry enough. Protein drinks when I used them made me very hungry and made me gain weight quickly.

But ok, since you are calling my bluff on this one I will find you some sources on the "bad for you" part. Until then I'll say it's related to the high temperature processing necessary to separate it and the lack of natural vitamins and fat. If it is hydrolzyed it has lots of glutamate (msg) too. But I'll get back to you on a few sources within a day or so.