I think the big culprit of the 40-50 age slot is the fact that you ususally don’t have the time to take care of yourself as you did in your 20-30-40 slot (more kids, longer working hours, more stress, less time to exercise / eat right). Plus, the overall lifestyle (more simchas to attend, later nights, more driving) work against you
Making a meal at home takes time and focus. Buying take-out on the way home takes $40. Walking 3 miles takes about an hour and burns calories; driving 50 miles burns gasoline.
Convenience is a great thing. But it also takes a great toll.