My friend is 23 years old. He was diagnosed with a binge eating disorder. Is binge eating a mental illness?
Yes
Yes. There is even a medication with FDA approval for it
Yes, it is a mental health disorder.
This site will address your question:
https://www.bustle.com/articles/72927-is-binge-eating-a-mental-illness-5-facts-about-the-disorder-you-should-know