Researchers found that obese individuals with elevated levels of fat in their liver, muscle tissue, and blood also have higher fat levels in their bone marrow, increasing their risk for osteoporosis. Study results were published online in Radiology.

The findings counter previous thinking that obesity has a protective effect against bone loss, said lead author Dr. Miriam Bredella, a radiologist at Massachusetts General Hospital and an associate professor of radiology at Harvard Medical School, in a statement.

Bredella and colleagues used MRS to examine 106 men and women between the ages of 19 and 45 years, who were obese based on body mass index but otherwise healthy. Subjects with more liver and muscle fat had higher levels of fat in their bone marrow, regardless of body mass index, age, and exercise status, the researchers found.

In addition, HDL cholesterol was inversely associated with the fat content of bone marrow, while triglycerides positively correlated with bone marrow fat.

The group focused on bone marrow fat because that is where stem cells can develop into either fat cells or osteoblasts, which are responsible for bone formation, Bredella noted.