A study published in the Jan. 27, 2015, issue of The BMJ challenges the longstanding notion that weight gain protects against postmenopausal fractures. Data from the Women's Health Initiative (WHI) indicate that weight gain, as well as weight loss, is associated with increased risk of fractures in postmenopausal women. The analysis also suggested that which bones were most likely to break depended on whether women have gained or lost weight.

WHI researchers analyzed data on over 120,000 healthy postmenopausal women ages 50 to 79 at the start of the study. Each year, participants were weighed and asked to report fractures of their arms, legs, hip, pelvis, and spine.

During an average of 11 years of follow-up, weight loss was associated with a 65% increase in hip fractures, a 9% increase in arm fractures, and a 30% increase in vertebral fractures, compared with a stable weight (less than a 5% change in weight). Weight gain was associated with a 10% increase in arm fractures and an 18% increase in leg fractures.

If there is a message from this study, it's this: if you are postmenopausal and are either losing or gaining weight, talk to your doctor. You may need to take extra measures to protect your bones.