Originally Posted by
OBoile
IIRC the total KJ burned is very close to the total number of Calories burned as well. Basically the ratio of KJ to kcal is very close to the ratio of the amount of mechanical force being generated to the total amount of work being done as most of the energy you expend is wasted as heat. Because of that, I pretty much only look at the KJ and use that to estimate the number of Calories.
I believe that the conversion factor from KJ to KCal is roughly equal to the metabolic efficiency of a typical person, so they tend to cancel out and KJ expended tends to be roughly calories burned.
dave