If you're not yet familiar with the three Japanese words hara hachi bu, it's time to add them to your vocabulary. The Confucian Okinawan adage translates to eating until you're 80% full. It is said like a prayer before every meal as a friendly reminder to practice mindful eating—consciously consuming each bite and cutting yourself off before you overeat.
There is a science behind the traditional, healthful strategy. There is a delay between your stomach becoming full and your brain recognizing it (hence the uncomfortable feelings of being too full that can suddenly hit you minutes after you've enjoyed a meal). Slowing down as you eat, and pushing the plate away when you feel like you've reach 80% fullness, will compensate for this delay in communication between your stomach and your brain. Integrating this phrase into your day-to-day will ensure you never stuff yourself, improving your digestion and helping you maintain a healthy weight and improve your longevity.
Here's another habit that people who live longer all practice.