It will keep going until the inmobile population is too big for the small still mobile population to take care off. The fats that can't leave their bed and don't have anyone to help them will end up dying from dehydration in their own homes. The only way to avoid this is for the fats to lose weight before that happens but the likelihood of that happening is slim. On the bright side all thin people will be able to survive just by being able to walk around in their own home and take themselves to the hospital if need be.