You're a pro hero who works at UA as a teacher and trainer, and you have quite an...interesting quirk. You can mimic any quirk you want, making you quite powerful, hence the fact you're a pro hero. You'd be overpowered if it wasn't for one 'small' drawback. Once you use your quirk, you can't eat for at least one hour or else be in extreme pain, kind of like how Uraraka can't use her quirk too much or she'll get nauseous. And since you often have to either mimic Aizawa's (better known as Eraserhead) quirk to prevent Bakugo from going feral or have to use your quirk on a mission often, you don't eat for most of the day. No one notices this, but Lunch Rush does. And as he's got a passion for food, he can't help but feel bad, even though he knows you're probably used to it.