Why not just artificially expand the concession-stand to grocery-store release window?

The LAT reports on declining sales at movie concession stands, which seem to be dropping about at the same pace as overall movie attendance (around 9% last year):

AMC Entertainment Inc., which runs nearly 5,700 screens, sold $313.9 million worth of hot dogs, soda, popcorn and candy in its most recent three quarters, down 8% from the comparable period a year earlier, when concession revenue totaled $341.8 million. Carmike Cinemas Inc., operator of nearly 2,500 screens, said concession revenue in its last six months was $75.1 million, compared with $82.1 million in the comparable period in 2004, down 9%. Carmike’s spending on concessions during those six months slid even faster, from $9.1 million to $8 million, a 12% drop.

I wonder if there’s a way to target over-eating and compulsively-buying segments of the movie-going population and make more films that appeal to them. Do movies about fat people sell more concessions than movies about skinny people? If anyone has market research on this, let us know.