Nov. 30, 2010 (Chicago) -- Belly fat may be bad for women's bone health, raising their risk of osteoporosis, researchers report.
In a study of 50 premenopausal women, many of whom were obese, those who had more fat around the waistline were more likely to have low bone mineral density, an osteoporosis risk factor.
"We found that in young women, deep belly fat is bad for the bones," Miriam Bredella, MD, assistant professor of radiology at Massachusetts General Hospital/Harvard Medical School, tells WebMD. "We now know that abdominal obesity needs to be included as a risk factor for osteoporosis and bone loss."
Bredella presented her findings here at the annual meeting of the Radiological Society of North America (RSNA).
Not All Fat Is the Same
Previous research has suggested that excess body fat protects against bone loss and osteoporosis.
But not all fat is the same, Bredella says. Using MRI and CT images, she showed that women with excessive amounts of "bad" visceral or intra-abdominal fat have a more porous bone structure than women without visceral fat. On the other hand, women with excessive subcutaneous fat that lies just below the skin show normal bone structure.
She and colleagues studied women whose BMIs (body mass index) ranged from 19 to 46, with an average BMI of 30. A BMI of 18.5 to 24.9 is considered normal, a BMI of 25 to 29.9 is considered overweight, and a BMI of 30 or more is considered obese.
All underwent a special imaging technique called MRI spectroscopy that allowed the researchers to evaluate different kinds of fat, including fat in the bone marrow. CT scans were used to determine bone mineral density.
The more fat in bones, the lower a woman’s bone mineral density was, the study showed. The more visceral fat -- for example, women with apple-like figures that have fat around the waist -- the more likely a woman was to have lower bone mineral density.
Excessive deep belly fat is also a risk factor for heart disease and diabetes, says RSNA spokesman David Levin, MD, of Thomas Jefferson University Hospital in Philadelphia. He was not involved with the work.
No treatment has been shown to preferentially get rid of belly fat rather than subcutaneous fat, says Mary C. Mahoney, MD, professor of radiology at the University of Cincinnati.
Your best bet: Not gaining fat in the first place or getting rid of as much body fat as possible, she says.
This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.