I've been using the elliptical at my gym, and the calorie count it gives me is different than the calorie count I get from MyFitnessPal. I'd just assume the machine was more accurate, but since MFP has my height and therefore has a more accurate read of how out of shape I am, I'm thinking that might be correct. Does the elliptical machine assume I'm a 260-pound man who's 6'5"? Because in that case I'd be burning more than it thinks. Or does it even matter?

Today, for example, I did 20 minutes on the cross-training mode with a resistance of 10-12, and it told me I burned 250 calories. MFP says 20 minutes of elliptical burns 354 for me. I was sweating like crazy and felt like a noodle afterward.

Do any of you know if, for people who are way, way overweight like me, the machines might underestimate assuming we're in better shape? Or should I take the machine's estimate?

Here's a sticky thread on this subject: http://www.3fatchicks.com/forum/exer...-accurate.html

I personally wouldn't use either method. I wouldn't try to figure out how many calories you've burned. The only way it's possibly useful is if you are figuring out how many extra calories you can eat for the day, though almost everyone overestimates how many calories they burned and ends up eating back more than they actually burned.

Instead, just consider those mysteries calories some unknown number you can bank towards your weight loss. If you are more hungry on days you exercise, maybe add 100 more calories of high-nutrient, protein-dense food (cheese, Greek yogurt, fish, etc). I wouldn't try to eat back any more than that unless you are doing an intensive exercise (swimming/biking/running/kickboxing) 1+ hour a day.