WHY does the diet industry make millions from us being fat then rob us to get skinny?

This is how i see it, The diet industry makes millions or billions every year simply from selling us everything from pills, books DVDs to cosmetic stomach bands, but they wouldn't make profit if there were too many skinny people in the world, so fast food outlets are the biggest selling fat houses the western world has ever seen in the past 50 years, guess how much money THEY MAKE from making us FAT----2 way street, McDonald's on every street corner making millions making us obese, and round the other corner Mr atkins with some $15.99 books, Money on both sides, go figure. by the way don't say its our own fault, we know theres more to it than that