Japan

The Japanese favor the Confucian philosophy of hara hachi bun me, also called hara hachi bu.

An excerpt from the article 39 facts about Japan
It is a teaching of the Chinese philosopher Confucius, who determined the healthiest approach toward food, and states that people should stop eating at 80% fulness of the stomach. This is one of the main reasons why the Japanese are among the healthiest nations in the world.