How many calories are you really burning on cardio machines?

I'm trying to get back into shape after my surgery, and I've been hitting the elliptical machine a lot. A few days ago, I was talking to my boyfriend about my workout, and he shook his head when I told him I had burned about 500 calories on the elliptical. He works at the UF gyms and sees people working out all the time. All these girls think the elliptical machine is the greatest thing ever, he said. But that calorie counter is not accurate. I, of course, defended the elliptical machine and told him that it was a fine workout ... but I wasn't really sure. Was he right? How many calories was I burning?

Unfortunately, there isn't a clear answer. From my Internet research I found that treadmills and stationary bikes have the most accurate calorie counters because they've been around the longest and have been researched and revised. Elliptical and other newer cardio machines have less accurate calorie counters because they haven't been researched a lot yet.

I found some basic tips to think about when working out on cardio machines:

The machines that ask for your weight will give a more accurate account. If you don't give a machine your weight, it usually bases its calculations on a 154-pound male. So if you weigh much less or much more than that, the calories reading you get ont he display console could be way off.

Your individual metabolism affects how many calories you burn. If you have a higher lean body mass you will burn more calories.

The machine assumes you're going at a certain speed or intensity. If you hang on the rails, do "baby" steps on the treadmill or otherwise "cheat" in your workout, the machine doesn't know it. If you put your feet on the rails of the treadmill, slalom skiing style for three of your 30 minute workout, you will have burned less calories than the machine says. Don't cheat.

Equations used by the manufacturers to determine calories burned may have been based on people who are not yet comfortable with the machine. You burn more calories doing something new than something you've done for a while. So the longer you work on a particular machine the less calories you may burn.

I felt better about myself after my research. Although I didn't get the straight answer I was hoping for so I could prove the boyfriend wrong, I did feel more educated and ready for more workouts. However, I will take my workout summaries with a grain of salt next time I hit the gym.