He asked whether I was interested in buying. I told him that I wanna reduce the amount of fat I have, then maybe I will consider getting it (I am a bit skeptical towards protein powders

He says that whey protein helps in reducing the fat from the body. I was taken aback by that coz as far as I have read forums or researched, it just gives you immediate protein. And the one he was talking about was just whey protein. No supplements.
How much of that is true ?