Quote Originally Posted by melodious fellow
The amount of calories one burns is directly correlated to the person's heart rate. If weed makes your heart rate increase, the rate at which the body consumes energy would also increase in theory, but nothing significant.
Sorry, but the amount of calories a body burns is directly correlated to that person's metabolic rate, not his heart rate.

Cardiovascular exercise, by working the large muscle groups and getting the heart muscle pumping, helps burn calories by building more muscle tissue, which is metabolically more active than fat, and by its contribution to increasing the rate at which the body uses calories. That's the metabolic rate. You can read more about it here.

MedlinePlus Medical Encyclopedia: Physical activity