Quote:
Originally Posted by Tyrone Slothrop
Why aren't calories burned a simple function of work performed -- a matter of weight multiplied by energy easily measured by the machine? Different bodies will be more and less efficiently in mobilizing to get this work done, but if you jump on a machine and expend (say) 500 calories of energy in moving its steps or pedals, why isn't that much easy to measure?
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The machine is not measuring how many calories you are expending. It is measuring, e.g., how many watts you produce, or what your MPH is. If I can hold 24 MPH on a spin bike for an 30 minutes without a major expenditure of effort, I am burning fewer calories than a person who needs to work really hard to hold that speed. Heavier people people burn more calories than lighter people do maintaining the same output (watts, MPH, however you are measuring it). Males and females burn calories differently. People who are the same weight but have different fat content and muscle masses burn calories differently. The treadmill has no idea how many calories it is taking you run X miles at Y MPH. It just knows that you did it and gives you a calorie burn based on something like what a typical 150 lb man would burn.
