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How Many Calories Did I Really Burn?

by michael on May 5, 2010 · 5 comments

The other day, I burned 992 calories during an hourlong session on the elliptical. Or at least that’s what the control panel said when I got done. But did I really burn off that many calories as a result of my workout?

I’m not really questioning the accuracy of the calculation itself. We have a pretty nice LifeFitness elliptical, and it factors in both body weight and heart rate when estimating calorie burn, so it’s probably doing a decent job.

The bigger problem lies in what is being estimated. Most exercise equipment estimates the total number of calories burned during your workout, rather than the number that were burned as a direct result of your exercise.

In other words, it’s estimating your total calorie burn instead of your net calorie burn. The distinction lies in that fact that you’d have burned at least a few calories during the time that you spent working out whether or not you had exercised.

Estimating net calorie burn

To make things a bit more concrete, let’s consider my resting metabolic rate (RMR), which I’ve previously estimated to be around 2140 calories. That means I’m burning an average of 2140/24 = 89 calories per hour just by being alive.

Subtracting this out of the 992 calories that I burned while on the elliptical for an hour and we’re left with a net calorie burn of 903 calories. Still an impressive number, but a bit lower than it first appeared.

The reason this matters is that you might end up double-counting a portion of your RMR if you take these calorie burn estimates at face value. The end result is that your estimate of calories burned in any given day will be high, and you might end up gaining weight, or at least losing it more slowly than you expected.

What good are calorie burn estimates?

The bottom line here is that you need to be careful when tracking your calories burned. I like the estimates provided by our exercise equipment for comparing across workouts, but I don’t interpret them literally. A much better metric for me is my actual weight loss.

If my weight’s going down, then I know I’m burning more calories than I’m taking in. I can even estimate my daily caloric deficit (or excess) using the 3500 calories per pound rule of thumb. For example, if I lose one pound over the course of a week, then I’ve had an average daily deficit of 500 calories.

For more thoughts on net calorie burn vs. total calorie burn, be sure to check out Mac’s post, where he concludes that 15% of a typical male’s total calorie burn while running would’ve happened whether or not they were running.

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{ 5 comments… read them below or add one }

1 H Lee D May 6, 2010 at 12:05 am

You were hauling on that elliptical! I only burn about 600 or so in a spin class.

You’ll also want to get enough sleep to aid in weight loss: http://change-is-possible.net/.....ories-out/

2 fitman May 6, 2010 at 8:23 am

I have an unwritten goal of breaking 1000 calories in an hour. I’m getting very close. :)

(Oops, now it’s written…)

As for the actual number, I really don’t know if it’s accurate or not, but it’s consistent across workouts, and gives me a relative benchmark from one day to the next.

You’re not the only one surprised by the high number… My wife spends a similar amount of time on the elliptical with a similar target heart rate, but she burns many fewer calories. I don’t think it takes gender into account, but it does factor in weight. I’m 6′5″ and 235-240 pounds — my wife is 100 pounds lighter. I’m thinking that must be the biggest reason for the difference.

Also: Interesting link on sleep and weight loss, thanks for pointing it out.

3 Joe May 10, 2010 at 4:16 pm

What about calories burned in recovery? Any numbers on that one?

4 fitman May 11, 2010 at 10:08 am

Joe: That’s a great question, and I don’t have an answer.

5 cryncrosalee January 4, 2012 at 3:28 pm

must look at this dvd to mov for more dvd to mov , for special offer

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