Weight-Loss Surgery and Women's Osteoporosis Risk

By Lisa Nainggolan
WebMD Health News

Reviewed by Brunilda Nazario, MD

May 12, 2015 -- Women who get weight loss surgery have a higher risk of thinning bones (osteoporosis) and fractures over time, according to a new analysis of a Swedish obesity study.

The findings don't seem to apply to men, the researchers say. They presented their analysis at the 2015 European Congress on Obesity.

Women in the study had one of three types of weight loss surgery. An early review shows those who got a gastric bypass operation had the highest risk of fractures and osteoporosis.

The cause of the higher osteoporosis risk isn't clear, says Sofie Ahlin, MD, PhD, of the University of Gothenburg. Malnutrition, which could restrict the body's ability to absorb certain vitamins and minerals, may be a culprit. Women who get weight loss surgery should take vitamin and mineral supplements, Ahlin says.

Details of the Study and the Analysis

The Swedish study began in 1987, and it's following 2,010 people ages 37 to 60 with a body mass index (BMI) of more than 34 for men and more than 38 for women. The participants had weight loss surgery between 1987 and 2001.

Of them, 376 (19%) had gastric bands fitted, 265 (13%) had gastric bypass surgery, and 1,369 (68%) had a type of surgery called vertical banded gastroplasty, which is no longer used often.

They were compared with 2,037 obese people who got treatments that didn't involve surgery.

To look into the effects of surgery on fractures and osteoporosis, Ahlin and her colleagues cross-checked the study subjects' info with reports of osteoporosis and fractures from the Swedish national health registers database.

As the years went on, there were 187 fractures among the surgery group compared with 127 in the other non-surgery group, after researchers adjusted for things like age, gender, smoking, and alcohol habits.

When the researchers broke down the gender info, it showed women – but not men -- who had had weight loss surgery were at significantly increased risk of fractures. They women who had surgery were almost three times more likely to get osteoporosis.

Take-Home Opinions

The findings add osteoporosis to a list of weight loss surgery complications that women -- who make up 80% of the patients for these operations -- should be aware of, says Dr. Sigrid B Gribsholt, from Aarhus University Hospital in Copenhagen, Denmark.

"It should not be a cosmetic procedure," she says. Women considering surgery should be told of all the risks involved and the steps they can take to help limit the risk of complications.

More and more teenagers are getting weight loss surgery, too, Ahlin says. Questions about their bone health afterward will need to be investigated.

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SOURCE: 2015 European Congress on Obesity, Prague, May 6-9, 2015.

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