I've stumbled upon interesting numbers that show an average body mass index in the world. 70% of US adults are overweight, many developed countries have nearly the same percentage: Canada - 67.5%, Germany - 62.8%, UK - 67.2%, and so on. But take a look at Japan - 29.4% of adults are overweight. An average life expectancy - 84.6 years.
There is an island in Japan, Okinawa. People there are famous for their longevity. Their diet can be the largest factor in such life expectancy. The residents don't eat for a full belly. They say you should be 80% full. How to determine this level? In simple words, you eat until you feel you're full. Maybe slightly hungry.
There are other secrets to this diet, but remembering to not eat until you can't move is worthwhile.
Why so? I presume it forces your body to redirect a lot of energy to digest food. One becomes lazy or sleepy instead of feeling refilled and full of energy.