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Discussion Starter · #1 ·
Before things got horribly off track, I was going to write to Dani's thread about exercise machines. How accurate are the calories counted?

In short: (1) not very, but (2) still accurate enough to be useful. Exercise machines take a limited amount of data--usually your weight, and the intensity of the exercise (speed + resistance) to give an estimate of the amount of energy you are metabolizing (METs). These estimates are based on formulas developed out of studies in which researchers gathered data on a lot of people as they exercised, and then they took all those data and created equations to describe the curves under different conditions.

So what you are getting is an estimate about how much energy a hypothetical person of average fitness might be burning on this exercise. That may or may not be an accurate reflection of how your own body is working at this minute. For example, it cannot take into account your level of fitness--unfit people are less efficient at burning calories, obviously, and so lower work will result in more calories burned than would be the case for a fit person. As you get fitter, chances are that the calorie counters will become less and less accurate.

In the broad scheme of things, though, how accurate do they really need to be to be useful? I and many other people have used the shorthand for years that a mile is about 100 calories burned. Is that really true for me all the time? No. But when I have been running longer distances (40+ miles per week) and upped my calories by roughly that amount, I maintained my weight. For most people, the counters give you a general sense of how many calories you are burning during exercise, and if you are losing weight you can then calculate how much additional calorie restriction you need to get to your goal deficit. If you find that you're not losing weight as quickly as you'd like, then you figure that the calorie counter is off and you restrict a little more. I find that taking the number given by the machine and multiplying by .75 works for me. (The manufacturers seem to be a bit overly optimistic, maybe to keep us feeling that we're doing something worthwhile. ;) )

So the basic point is true that although the absolute number is off, the rate should be reasonably consistent. Contrary to deific's assertion, most people are not going to have such a dramatic change in body composition or fitness in a few months that they will become so efficient as to alter the pattern in a nontrivial way.

Is that helpful?

My elliptical doesnt let me add in my weight, so it is definately not counting them correctly for me.
Don't they generally take an average of 135-135 lbs and do their calcuations from there?
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