Calorie burn ????

hilarysgiants

I have an HRM to help determine my calorie burn for the P90X DVDs. I see other people posting that they burn double doing the same exercise. I put all my efforts into the workouts. I am guessing this is due to my age and weight now. I can't seem to get my heart rate into my fat burning range either, but not sure that i calculated that properly. I am 34 and my RHR is 60. I am 5'3" and weigh 130. Trying to tone and hopefully get around 120 or at least get rid of my belly jiggle!