Children with lean body mass build bigger bones compared to the ones who have greater percentage of fat, according to a research.

Howard Wey, professor at South Dakota State University (SDSU), said that they were interested in relative influence of lean mass, which is muscle, versus fat mass on how bone grows as children grow.

Wey and colleagues analysed data by taking bone and body composition measurements of rural children in South Dakota.

Wey said that a larger child will have larger bones because he is heavy. But, if there are two kids of same weight, the one whose weight is dominated by fat mass is more likely to have smaller bones than the one whose weight is dominated by lean mass. Larger bones are stronger than weaker bones.

The project has already tracked more than 1,700 individuals over a three-year period to evaluate how lifestyle affects bone density in three groups of people.

To study fat mass versus lean mass as a factor in bone development, SDSU researchers gathered two to three measurements over a 36-month period on about 150 male and about 200 female children aged eight to 18.

Because they are growing children, all the children in the study showed increases in bone mass, area and density. But there were clear differences in rates of change.

Wey said that kids with higher lean mass, or muscle, tended to have greater rates of change, and kids with higher fat mass tended to have lower rates of change.

These findings were presented at the annual meeting of the Paediatric Academic Societies in Baltimore.