Is in the wrong room.
The quickest way to ensure you don't grow is to assume you know more than the person next to you. It takes away your need to ask questions.
If you already know, why would you ask?
Roughly every ten years, most of what scientists believe is considered a healthy diet, changes. What they thought they knew a decade ago, isn't taken seriously today.
What you think you know today, might not be right tomorrow.
Ask more questions than you answer.
Listen more than you speak.
And if you notice you're the smartest person in the room, it's time to change rooms...or at least the subject.