We’ve long had a theory-and not a very sophisticated one-about why weight loss shows are so popular (even if no one will admit to watching them). It’s this: watching other people diet and exercise means you don’t have to! Somehow, simply witnessing the miracle (or torture) of other people getting in shape and eating right, cheering them on, makes viewers feel a little better about themselves, too. (This may be because, compared to a morbidly obese person, our post-college 20 pound gain doesn’t seem so bad.) Anyway, maybe Alessandra Stanley’s piece over the weekend made ABC realize that they, too, should get in on the game that NBC (and the Discovery Channel , and the N network for teens, and even VH1) has profited by with The Biggest Loser, I Can Make You Thin, The N’s Student Body and Celebrity Fit Club. Daily Variety reported late yesterday that the network will team with People Magazine for an hour long special to be broadcast September 30th at 10pm called “Half Their Size: The People Magazine Weight Loss Challenge.” No celebs here! Just the overweight residents of Mississippi, our fattest state. More news: If ratings are healthy (the joke is Variety’s not ours), we may be treated to this special annually.