I thought it was crazy too, but the Seniors were active and healthy. They just got to the point, they said where they dont need as much. Here is one article about it. There are many.
http://www.time.com/time/specials/pa...963381,00.html
there is also a case study called the "Okinawa Study" that talks about it.
Basically it is about slowing down the caloric intake, but maintaining the nutrient value.
1200? I wish! I just started tracking/limiting, and I am at 1800. I would love to get to that point!