Re: How many calories would you burn in a one hour class?
As someone who has managed to lose 9% bodyfat this year I'd just like to add my thoughts in the exercise vs diet debate.
The obvious answer is a good mix of both (weights are great, muscle is a real calorie burner). The conclusion I came to was to consider exercise primarily for cardio benefits and to increase muscle for base metabolic rate, and diet for weight loss.
In other words, you can't counteract a poor diet with exercise. Exercise can only supplement a good diet in weight loss.
It's all about calories in vs calories out at the end of the day, and it's much less effort not to eat lots of saturated fats than it is to burn them off!