Weak Bones Linked to Obesity

Obesity could cause weaker bones according to new research conducted at the University of Georgia. The study, published in the American Journal of Clinical Nutrition, finds that obesity could adversely affect bone health, making bones nearly 10 percent weaker than comparable bones found in non obese individuals.

In the study, 115 women who were ages 18-19 were given bone scans. They were divided into two categories, women with normal body fat, which was identified at less than 32 percent, and high (larger than 32 percent) body fat. The researchers adjusted for the muscle mass around the bone, and found that obese individuals had bones that were 8 to 9 percent weaker.

"Obesity is an epidemic in this country, and I think this study is critical because it highlights another potential negative health effect that people haven't considered," said study co-author Richard D. Lewis, professor of foods and nutrition at the UGA College of Family and Consumer Sciences.

Other studies looking at the connection between obesity and bone health had used a two dimensional bone densitometer to determine the health of the bones. This machine is typically used as a diagnostic tool for osteoporosis. However, the densitometer does not give a clear picture of the bone shape, leading to incomplete information about bone strength.

By using a three dimensional imaging technique, both the mineral component of the bones as well as the bone shape (which also affects bone strength) could be determined. Researchers were surprised to find that without adjusting for muscle mass, both groups of women had similar bone strength.

Traditional wisdom suggests that obese women would develop more bone strength, because they often have more muscle. Muscle creates force on the bone, which actually encourages bone growth. This fact caused many researchers to assume that being overweight would actually be good for bone health.

"The fact that the two groups had similar bone strength measures is remarkable in itself, because you would expect it to be higher in the heavier person," Lewis said.

Norman Pollock, who also worked on the study, elaborated saying ""When we corrected for the amount of muscle, we found that the obese person is not making as much bone as they should be for the amount of muscle that they have. People haven't observed that in the past because they weren't using the three-dimensional scan."

While researchers are not sure how fat lessens bone strength, they did not that studies on rats indicated that obese rats created more fat cells in the bone marrow coupled with fewer bone cells. This may indicate that fat production is preferred over bone production in obese people. Source:

University of Georgia, "Study suggests link between obesity, poor bone health" Eurekalert