3 ideas
Ekken treats the pleasure of eating and the harm of eating as arriving at different times: the pleasure is immediate, but the damage from the last few mouthfuls shows up hours later. His rule is to stop while some appetite remains, often summarized as eating to about eighty percent full.
Each person starts with a limited endowment of vital energy (ki), and every excess drains it. Overeating, heavy drinking, sexual excess, oversleeping, and strong emotions such as anger and worry all count as withdrawals from that endowment. Long life therefore depends less on adding tonics or remedies and more on cutting the leaks through daily restraint.
Ekken sorts threats to health into two kinds. Inner enemies are the desires (for food, drink, sex, sleep, idle talk) and the emotions (anger, grief, fear, anxiety), and these must be restrained. Outer enemies are wind, cold, heat, and damp, and these must be avoided or guarded against, so each threat calls for a different response rather than a single rule of 'be careful.'