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28 January 2011

Issue 108: From Jordan's Desk - Bone Fat?

It sounds like a contradiction in terms, but having too much fat in the bones can lead to thinning bones. What’s more is that this negates previous research which suggested that carrying extra weight and fat protected women against bone thinning and loss.

Here’s the skinny on the bone fat: Women with too much fat around the middle may compromise their bone health and be at greater risk for osteoporosis. Doctors at Massachusetts General Hospital studied 50 premenopausal women with an average body mass index (BMI) of 30. The women’s bone marrow fat and bone mineral density were also measured to determine their bone mass and bone loss.

The researchers were particularly interested in visceral fat—a kind of fat that exists below the muscle tissue in the stomach—compared to fat that is located just under the skin called subcutaneous fat. Visceral fat is believed to be the more dangerous of two, as it has been implicated in greater risk of heart disease. In this case, the doctors wanted to see if there was a difference in osteoporosis risk dependent upon which kind of fat the women had more of.

The doctors used imaging tests to discover that the study’s participants who had more visceral fat also had more bone marrow fat and less bone mineral density—which translated into a greater risk for osteoporosis. Interestingly, the researchers found no significant link between subcutaneous fat or total fat and bone marrow fat or bone mineral density.

Dr. Miriam Bredella, a radiologist at Massachusetts General and assistant professor of radiology at Harvard Medical School, was the lead author of the study. She says, “Our results show that having a lot of belly fat is more detrimental to bone health than having more superficial fat or fat around the hips.”

There may be more to the story, though. Dr. Leanne Chrisman, a family medicine doctor at University Hospitals Case Medical Center in Ohio says, “The people who consume the most unhealthy carbohydrates and fats are the ones going to be the most obese, and they’re also the ones who are the most likely not to exercise. Weight-bearing exercise is associated with improved bone marrow densities. A lack of exercise is associated with being obese and low bone mass.” Additionally, says Chrisman, the more visceral fat you have, the more difficult it is for you to absorb nutrients that are crucial for good bone health, like calcium and vitamin D.

Lead study author, Dr. Bredella sums it up: “It is important for the public to be aware that excess belly fat is a risk factor for bone loss, as well as heart disease and diabetes."

So, if you need one more reason to lose that tummy…now you have it.

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