Using stable isotopes to assess reduced physical activity of individuals with Prader-Willi syndrome

The contribution of reduced levels of physical activity to the positive energy balance found in most individuals with Prader-Willi syndrome is not known. We assessed total energy expenditure using stable isotopes and resting energy expenditure using open circuit indirect calorimetry in a group of 10 children with this syndrome. The difference between these two measures is primarily the energy cost of activity and is often called a physical activity level. After adjusting for age, we found that the physical activity level values of these children were significantly reduced in comparison to children who did not have Prader-Willi syndrome. Increasing activity levels in children with Prader-Willi syndrome will raise total energy expenditure and may help to control their development of weight gain.