Talk about forgetting to eat when studying.

I am so diligent that I forget to eat.

Confucius in The Analects of Confucius said: "Women forget to eat when they don't say they are human, and forget their troubles when they are so angry. I didn't know she was getting old.

This idiom describes Confucius' hard work or study.

In modern times, it means studying or working hard and even forgetting to eat. It is often used with "taking pleasure in forgetting worries" to describe being very diligent.