Although adults who lose weight may also lose some bone mass, obese adolescents seem to keep gaining bone density as they shed pounds, a study suggests.

The findings, reported in the medical journal Obesity, offer some reassurance that obese children’s weight loss may not come at the expense of their bone health.

The study included 62 obese adolescents who completed an intensive year-long weight-loss program and had X-rays to chart changes in their bone mineral content. The researchers found that even as the teenagers lost weight, their bone mass continued to increase and remained higher than that of a comparison group of thin adolescents.

“Our findings suggest that successful, medically supervised obesity treatment in adolescents does not cause major problem for bone health,” said lead researcher Dr. Nicolas Stettler of The Children’s Hospital of Philadelphia.

Given the many health benefits of weight loss for obese children, concerns about bone development should not keep them from getting help for their weight, Stettler told Reuters Health.

Some past studies have found that overweight and obese children are at greater risk of bone fractures than their normal-weight peers. The reasons are not certain, since a few studies, including the current one, show that obese adolescents typically have greater bone mass than thinner teens do.

Factors unrelated to bone mass may help explain the higher fracture risk, Stettler and his colleagues note. For example, falls may be harder on obese children owing to their extra weight or poorer coordination.

In theory, losing weight might lower obese kids’ odds of sustaining a bone fracture, according to Stettler. But, he said, this has not yet been proven in studies.

SOURCE: Obesity, February 2008.