High-Tech Devices Help Gauge Calories Burned

By Marcia Wood
October 14, 2003

Three new, high-tech devices may help in the fight against obesity, America's No. 1 nutrition problem. The instruments make it easier, faster, and less expensive to determine how many calories a person burns during any given day.

Agricultural Research Service physiologist Mary J. Kretsch at the agency's Western Human Nutrition Research Center in Davis, Calif., is leading a study of the new instruments. She's determining their accuracy and the best combination of them for researchers and healthcare professionals to use in helping their patients maintain a healthy weight. These professionals include nutrition researchers, dietitians and physicians, especially those specializing in bariatric (obesity) or sports medicine.

Two of the instruments are lightweight, pocket-size "activity monitors" for use in calculating the number of calories burned through physical activity. Worn attached to a belt or waistband, the monitors use motion-sensor technology to record the wearer's movements. That's unlike pedometers, for example, which simply measure forward strides. The sophisticated new meters, in contrast, record a wide range of the wearer's movement. Researchers can convert the movement measurements into total calories burned.

The third instrument, a convenient, hand-held device, may replace today's bulky "metabolic cart." The cart and the hand-held device both yield "resting metabolic rate," or RMR, the number of calories an individual burns while sitting quietly. Resting metabolic rate and physical activity together account for about 90 percent of the calories that people burn.

In the current phase of the study, Kretsch and colleagues are working with 20 healthy, normal-weight or overweight female volunteers, aged 25 to 40. The next phase, with a new team of women volunteers, begins this fall.

ARS is the U.S. Department of Agriculture's chief scientific research agency.