Supersize people eat so much we may run out of food...
http://now.msn.com/living/0618-obesity-threatens-food-supply.aspx
http://now.msn.com/living/0618-obesity-threatens-food-supply.aspx
I heard all the extra weight is slowing the earths rotation, cause seasons to be longer...

The fat people will be the first to die from global warming though, their bodies can't handle the heat...on the other hand if we end up in another ice age then they'll rule the earth.
I know you're joking but I'm going to take this opportunity to point out the circle of life/law of conservation of mass. We're not getting this extra food from outer-space or the moon or anything...