How annoying but I don't know?

I'm really thin! Specially for my age I'm about to turn 22 and I weight 100 pounds and it's very annoying. So, I've heard that when you eat at night it makes you gain a lot of weight so I keep eating every night. Anyways my co-workers are always giving me a lecture how this will affect my future of my bad habits but yet, they don't understand my need to gain weight and actually feel my age not feel like a 16 year old😩