Is it normal to not want to eat even though you're hungry?

This has nothing to do with weight. I'm very comfortable with my body and I realize that I'm a little underweight, though this is mainly due to a genetic disposition. However, I'm not very comfortable with anything else about myself. Even though I'm hungry, sometimes I'll put it off thinking things like, "I don't deserve to eat". In high school, I would opt out of eating lunch and instead use the time to do other things, like homework, because it was more productive or important. Essentially, I treat eating like a luxury more so than a necessity and I have no clue where that attitude towards food came from. Is it normal?