Fat in organs may increase osteoporosis risk

Excess fat in your liver, muscle and blood may be a risk factor for weakened bones, a U.S. study said Tuesday. The study, published online in the journal Radiology, found that obese people with higher levels of fat in their liver, muscle tissue and blood have higher amounts of fat in their bone marrow, putting them at risk for osteoporosis. "Obesity was once thought to be protective against bone loss," said lead author Miriam Bredella, a radiologist at the Massachusetts General Hospital and associate professor of radiology at the Harvard Medical School in Boston. "We have found that this is not true." Previous studies have examined the relationship between visceral fat and bone mineral density. This study, however, looked at fat inside bone marrow where osteoblasts, or the cells responsible for new bone formation, live. Bredella and her colleagues used proton magnetic resonance spectroscopy, a technique that allows for precise measurement of fat, to examine 106 men and women, aged 19 to 45 years, who were obese based on body mass index measurements, but otherwise healthy. The results showed that people with more liver and muscle fat had higher levels of fat in their bone marrow, independent of body mass index, age and exercise status. They also found that high levels of triglycerides, the type of fat in the blood, were linked with higher levels of bone marrow fat. "Bone marrow fat makes bones weak," Bredella said. "If you have a spine that's filled with fat, it's not going to be as strong."