Excess weight, along with a low amount of muscle mass, during a child’s adolescent years may put the child at risk for weakened bone structure in adulthood, according to researchers.

“While obesity was previously believed to be protective of bone health, recent studies have shown a higher incidence of forearm fractures in obese youths,” says Miriam A. Bredella, MD, radiologist at Massachusetts General Hospital, associate professor of radiology at Harvard Medical School in Boston, and lead author of the study.

The study, presented at the Radiological Society of North America (RSNA) annual meeting, involved 23 obese adolescents, with a mean age of 17 and a mean body mass index (BMI) of 44 kg/m2.

Bredella and her research team performed 3D HR-pQCT—a type of computed tomography exam designed specifically for measuring bone mineral density and bone microarchitecture in the arms and legs—to determine the bone structure of the distal radius, an area of the forearm near the wrist. They also performed dual-energy x-ray absorptiometry (DXA) exams to determine body composition, including lean mass and visceral fat mass. Visceral fat is the deep fat in the abdomen that surrounds the internal organs, explains a media release from RSNA.

“There are several mechanisms by which visceral fat exerts negative effects on bone,” Bredella states in the release. “Visceral fat secretes substances that promote chronic inflammation, and chronic inflammation stimulates formation of osteoclasts, which are the cells that resorb or break-down bone. In addition, vitamin D, which is important for bone health, is soluble in adipose tissue and gets trapped within fat cells.”

Growth hormone, which is important for bone health, is also lower in adolescents with visceral obesity, she notes.

According to the results from the study, BMI is positively associated with cortical thickness and area. Cortical bone is dense and compact and forms the outer shell of most bones. Visceral fat mass is positively associated with cortical porosity.

In addition, lean mass is positively associated with trabecular density, volume and integrity. Trabecular bone is a spongy inner layer of bone that provides support and flexibility.

“The best way to prevent bone loss is a healthy diet that contains adequate amounts of calcium and vitamin D, along with sufficient exercise, as we have shown in our study that muscle mass is good for bone health,” Bredella concludes.

[Source(s): Radiological Society of North America, PR Newswire]