Aesthetics is a branch of philosophy dealing with the nature of beauty, art, and taste, with the creation and appreciation of beauty.
And it doesn't just affect girls. Guys are getting really big on aesthetics feeling that their slim non-muscular phsyicques are just NOT good enough. Feeling they need to be ripped to get the hot girls and have sayings like "No pecs no sex."
Have you heard of Naso and his Facebook page for example? His page is called Nasthetics. Chances are your teen or young adult has heard of him.
Or perhaps you've heard of Zyzz? He's a young man who was all about aesthetics and sadly he passed away at a young age. Nonetheless he is still a hero for many young men wanting to achieve a ripped body like his.