Idols always peak in popularity, both among ifans and especially kfans, for their visuals when they are at their thinnest
no matter how obvious it is that they starved themselves, those pictures of side profiles with defined jaws ( and usually idols dont have super sharp faces ) will get the clicks and downloads
so even though EVERYONE is aware of whats bad for health, the motivating to starve is simply much stronger
celebrities can live off of praise and validation instead of food, it is their job after all, especially idols who care more about their looks than their skills