과유불급
過猶不及 · too much is the same as not enough
Overdoing something is as bad as not doing enough.
When to useToo much exercise, too much salt, too much advice.
Examples
영양제도 과유불급이야. 너무 많이 먹지 마.
Vitamins too — too much is as bad as too little.
Korean life dictionary
22 short guides to words and manners