The 12-year-old about his self-image: "I like myself"

Although the study from Lund University shows that middle school girls in Sweden have a good self-esteem, it also shows that it plummets once they reach high school.

Why do you think that is so?

- You enter puberty, you think of guys and you may want attention and then maybe the self-confidence disappears, says 12-year-old Danica Nikolic.

"In middle school you do not care"

Puberty also comes into play, Vibeke Palomo believes.

- Yes, then the body develops, you may start to question things, she says.

Minna Leander fills in:

- And it may be more important which gang you are part of, in the intermediate stage you do not care so much.

Hear more in the clip above about what Danica Nikolic, Isabella Gabor, Vibeke Palomo and Minna Leander say about their own self-esteem.