Insanity burned calories query.

According to my fit bit with HR monitor it burns about 250 for 30 minutes. I am working hard the whole time!

I do an Insanity class once a week, it lasts 45min and I seriously work my *kitten* off. How many Calories you burn is going to depend on a variety of factors including :

1. How much effort you put in, if you don't put your all into it you won't burn as many calories. I put my all in to each move so for me that factor doesn't change much.
2. How much you weigh, it takes more energy to propel 200lb in to the air than it does 150lb.
3. How fit you are, when I first started exercising it felt like I was dying when my HR went above 130, now it regularly hits 183 during Insanity and I can do so much more of the moves (couldn't even do a burpee when I started let alone one armed burpee)

To give an idea of how the Calorie count changes, 200lb me, in my first Insanity class burnt >600 Calories, despite my HR not going above 140 and having to heavily modify every move. My HR stayed high throughout the whole class as it took me a long time to recover.

Last week 150lb me, despite not needing to modify any moves and my HR peaking at 183, burnt <350 Calories, mostly because as well as being that much lighter I'm also exponetially fitter and my HR recovers much quicker. I still sweat buckets and still work just as hard (and sometimes feel like I'm going to vomit after the occasional power round), my body is just that much more efficient and I struggle to get anywhere near the Calorie burn I was getting a year ago.