Peter Weyand of Southern Methodist University and colleagues at Baylor College of Medicine say the equation uses height, weight and distance walked to calculate the number of calories burned.
"This goes back to Max Kleiber's work on resting metabolic rates for different sized animals," Weyand says in a statement.
"He found that the bigger you are the slower each gram of tissue uses energy -- it's interesting to know how and why metabolism is regulated that way."
The equation, published in The Journal of Experimental Biology, is based on the researchers' observation that walkers ages 5-32 of all heights move in exactly the same way. However, shorter people were taking more steps to cover the same distance and walkers' energy costs turn out to be inversely proportional to their heights, the study says.
Weyand and colleagues analyzed volunteers walking on treadmills. Oxygen consumption and carbon dioxide production rates were used to measure metabolic rates, the study says.