How many French fries did that 3-mile stroll burn off? It depends on how tall you are. When walking the same distance, short people burn more calories per pound of body weight than do tall people, simply because they have to take more steps to get there. That may seem obvious, but now researchers have proven it by measuring the metabolism and biomechanics of 48 children and adults walking on a treadmill. At a comfortable pace, study participants all took steps that were three quarters as long as their height. They also burned the same amount of energy per pound per step; short people just had to take more steps to cover the same distance. The study, published  today in the Journal of Experimental Biology, pulls height, weight, and distance together into a single simple equation that could make calorie-counting gizmos more accurate and help the military provision troops on extended marches.
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