Research Considers Lean Mass Better for Developing Bones

South Dakota State University research shows that a child with leaner body mass, or muscle, builds bigger bones than a child who weighs the same but has a greater percentage of fat.
 
“We were interested in the relative influence of lean mass, which is muscle, vs. fat mass on how bone grows as kids grow,” says Howard Wey, PhD, an associate professor in South Dakota State University’s College of Nursing.
 
“There’s a little bit of controversy because weight itself has a positive influence on bone,” says Wey. “Heavier individuals tend to have more bone just to support their weight.” The study was designed to look deeper at that issue to see whether there are differences in how lean mass and fat mass correlate with bone development.
 
“A larger child is going to have larger bones just because he’s heavier,” Wey says. “But if you have two kids at the 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. Smaller bones are weaker than larger bones.” The study is an offshoot of the ongoing South Dakota Rural Bone Health Study. To date the project has tracked more than 1,700 individuals over a three-year period to evaluate how lifestyle affects bone density in three groups of people: Hutterites, rural non-Hutterites, and nonrural non-Hutterites.
 
To study fat mass vs. lean mass as a factor in bone development, the researchers gathered two to three measurements over a 36-month period on about 150 male and about 200 female Hutterite children aged 8 to 18. Because they are growing children, all the children in the study showed increases in bone mass, area, and density, Wey notes. But there were clear differences in rates of change.
 
“We looked at multiple measurements over time. We found that lean mass had a positive effect on rates of change,” Wey says. “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.”

Source: South Dakota State University