One in three teenagers has been involved in bullying in the last year.
A huge new study across Europe and North America has shown boys fight more often than girls, but girls were just as likely to be victims as boys.
The report looked at many aspects of teenage life, and showed that kids were leading increasingly unhealthy lives by not eating or exercising properly.
It also revealed teens don't follow healthy food advice, and are less likely to have breakfast.
Studies show that eating breakfast has an effect on energy levels and the ability to study.
Fruit and veg aren't popular either, with less than one in three boys surveyed eating fruit daily.