You have to apply yourself to class. I hate when I tell people (online) that I attend a Zumba class, and they assume I'm a ZumbaFat. I use Zumba as some fun cardio time, and later lift. I wouldn't recommend Zumba as the primary source of exercise, but for me it adds some variety in the cardio division. That being said, there's a lot of fats in my class. :/