The reckless risk taking found among many adolescents is most likely due to the effects of

Oh that's nothing to worry about.  It's normal.  It's due to the effects of youth,
and the instinctive impression of immortality that comes with it at no extra
charge just pay shipping and handling. 

Adolescent reasoning goes something like this:  "Whaddaya mean
this is dangerous ?  Whaddaya mean I'm being reckless ? ! ?
Who says ?  I've been doing it for almost a week now and I haven't
died yet and I don't know anybody who died from it, so it can't be that bad,
and you don't know anything and you just don't want me to have any fun,
and I'm just gonna keep doing it at least until I need glasses."

This is what a calorimeter is used for simpler ex, to measure calories in food.