I recently bought a polar heart rate monitor so that I could get a more accurate idea of the calories I burned from exercise. Since the gym has been packed lately, I've been doing a lot of exercises dvds- Tae Bo- at home. I'm averaging about 350 calories burned in a 44 minute tae bo workout.
I took it to the gym for the first time and tried it out on the elliptical/arc trainer machine. I was there for an hour and at the end the machine said I burned 524 calories. I checked my heart rate monitor and -SHOCK- it said I burned 359. That's a huge difference!
I'm really glad I never tried to eat back the calories I burned through exercise or I would have made a huge mess