Excessive abdominal fat, also known as intra-abdominal fat, and informally as belly or tummy fat, can be bad for bone health, researchers from Harvard Medical School revealed at the annual meeting of the Radiological Society of North America in Chicago. This goes against the common belief that obese women have a lower risk of developing osteoporosis.

Lead Author, Miriam A. Bredella, M.D., a radiologist, said:

    “We know that obesity is a major public health problem. Now we know that abdominal obesity needs to be included as a risk factor for osteoporosis and bone loss.”

About 72 million US adults are obese, says the Centers for Disease Control and Prevention (CDC). An obese individual has a BMI (body mass index) of at least 30. Experts say obesity is linked to several health problems, including diabetes, hypertension, cardiovascular disease, joint diseases, some cancers, sleep apnea and asthma. However, it has been commonly accepted that obese women have a lower bone loss risk compared to other females.

There are different types of fat. The fat just below the skin is called subcutaneous fat, while visceral fat (intra-abdominal fat) is deep within the abdominal cavity, under muscle tissue.

How much visceral fat we have depends on several factors, including our genes, diet and how much exercise we do. Some studies have linked excessive fat levels to lack of sleep. Several researchers have linked high levels of visceral fat with heart disease risk.

Dr. Bredella and colleagues carried out a study examining fat levels and mineral densities of 50 obese, premenopausal women.

Each participant had an MR spectroscopy to evaluate bone marrow fat of the fourth vertebra in the lumber section of the spine – known as L4. With the use of QCT (quantitative computed tomography) they measured bone mass and assessed bone loss.

They found that the participants with higher levels of visceral fat also had more bone marrow fat and lower bone mineral density. The same correlation was not found between subcutaneous fat and bone marrow fat and bone mineral density.

Dr. Bredella said:

    “Our results showed that having a lot of belly fat is more detrimental to bone health than having more superficial fat or fat around the hips.”

18 million women have low bone mass, while another 10 million have osteoporosis in the USA, says the National Women’s Health Information Center. The two conditions increase the risk of subsequent diseases.

Dr. Bredella said:

    “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.”

The researchers say another study is currently underway with male participants – also determining whether visceral fat is a risk factor for bone loss.

“Detrimental Effects of Visceral Obesity on Bone Health”
Abstract – CODE: SSJ17-05
Radiological Society of North America – RSNA 2010

Written by Christian Nordqvist