Weight loss during menopause appears to be associated with increased rates of bone loss at the hip, the findings of a long-term study suggest.

Even women who are on hormone therapy are “not totally protected from bone loss,” Dr. Jane A. Cauley, University of Pittsburgh, Pennsylvania, told Reuters Health.

Weight change leads to changes in bone mineral density, she and colleagues note in a report in The Journal of Clinical Endocrinology and Metabolism, and weight loss during menopause may be particularly worrisome because of concurrent menopause-induced bone loss.

Cauley and colleagues had previously identified greater bone mineral density loss over an 18-month period among women in a lifestyle intervention program designed to promote modest weight loss (low-fat diet and increased physical activity) compared with women simply advised to follow a low-fat diet (control group).

They now report bone mineral density and weight measurements among the 373 non-obese premenopausal women, aged 44 to 50 years, followed for up to 78 months.

Over the 54-month active intervention period, the control group gained 2.6 kg of body weight while the intervention group lost 0.4 kg of body weight on average. However, Cauley notes, the annualized rate of hip bone loss was “6-fold greater” among women who lost weight compared with those in the control group who did not.

“Women who took hormones at the time of menopause experienced slower rates of bone loss,” Cauley said. “Nevertheless, if these women also lost weight, they experienced faster rates of bone loss.”

The researchers estimate a 5-year bone loss rate of about 7 percent among the women who lost weight. “This amount of bone loss has been associated with an increase in fracture risk,” Cauley adds.

When the researchers re-assessed the study population 2 years after the active intervention stopped, they found smaller between-group weight differences and “generally absent” differences in bone mineral density.

Cauley notes that the study findings should not discourage women from losing weight, if they need to, since being overweight is linked to a number of health problems. However, she suggests women instituting a weight loss program should be aware of the potential negative consequences on their bone health.

SOURCE: The Journal of Clinical Endocrinology and Metabolism, October 2007