The purpose of this study was to validate the Stayhealthy BC1 bioelectrical impedance analyzer to assess percent body fat in children and adults. The BC1 was compared to dual-energy x-ray absorptiometry assessment of body fat for adults and to hydrostatic weighing assessment of body fat for children. We hypothesized that the BC1 would provide similar measures of body fat between devices with acceptable limits of agreement.

The BC1 body composition analyzer is manufactured by Stayhealthy. It is a handheld, noninvasive bioelectrical impedance device. When held, the BC1 sends an electrical impulse through the body to determine body fat, muscle mass, and body hydration. Bio-impedance devices measure the change in electrical resistance in body tissues by using a detectable electrical signal that passes through the body. The method is based on the principle that lean body mass contains virtually all the water and conducting electrolytes in the body and provides a good electrical pathway. In contrast, fat or fat-containing tissues produce a poor electrical pathway. By inducing a low-energy, high -frequency signal, a measurement of the baseline resistance to flow of electrical current can be assessed. The resistance measurement relates directly to the volume of the conductor. Through repeated measurements and identifying other parameters (i.e. gender, weight, age and height) proprietary equations were developed that determine total body water, fat free body mass, and total body fat.

Inclusion Criteria:

• boys and girls 10-17 yrs and men and women 18-80 yrs

Exclusion Criteria:

• acute illness
• pregnancy
• pacemaker or defibrillator

Adverse events were monitored over the study but no adverse events were reported.