"That is, even two different people of exactly the same weight, height, age, gender, and activity level do not necessarily burn calories at the same rate." The

"That is, even two different people of exactly the same weight, height, age, gender, and activity level do not necessarily burn calories at the same rate." The AJCN (American Journal of Clinical Nutrition), has tons of paper on these types of topics, and one of the clever things they do is use isotopes of hydrogen and oxygen (Doubly Labeled Water, DLW), to get an exact measurement of a persons metabolic rate. They then use those exact measurements to do things like calculate how much the various activities like sitting, walking, typing, reading, running, sleeping, lying down quietly, etc... consume in terms of calories. What's nifty (and surprising to me), is that for most people, the standard models that are based on age, weight, height, and gender are pretty good predictors as to how much energy you will consume doing a particularly activity.