Okinawa Centenarian Study

http://okinawaprogram.com/study.html

The Okinawans stay lean by eating a low-calorie, unrefined-complex carbohydrate diet, practicing calorie control in a cultural habit known as hara hachi bu (only eating until they are 80% full), and keeping physically active the natural way. Okinawan elders are lean, with average body mass index (BMI) that ranges from 18 to 22 (lean is less than 23).

Personality testing found that centenarians, when in their prime of life, scored low when it came to feelings of "time urgency" and "tension" and high in "self-confidence" and "unyieldingness." Interviews revealed optimistic attitudes, adaptability, and an easy-going approach to life. Moderation was found to be a key cultural value.