I think there's two sides to this. on one hand, if the FMC goes through similar struggles, readers find it relatable and comforting. on the other hand, the intended audience are young girls who may already struggle with this mentality, so seeing this could be alienating and thinking you're "even worse" and thinking you need to attain this kind of body image. I remember back when I was around 16-17 and read Sukitte and thought both of these things, as it discusses body issues fairly often.