Most Americans Are Already Stocked With 35 Days of Emergency Rations

A pound of fat is 3500 calories.  Post-apocalypse, the 20 extra pounds most Americans carry should provide 35 days of 2000 calories each.  Yes, your body adjusts to calorie deficits by becoming more efficient in storing calories as fat but that means that most Americans could probably go more than 35 days on the World War III diet.  I am not saying it would be pleasant but having to subsist on 500 calories a day would not be impossible for a few weeks.  And my, would we be fit when it came time to rebuild!