Dieting teenagers risk bone diseaseSize zero bad for bones
Dieting teenagers who are under pressure to be thin may be putting their bones at risk, UK scientists have found.
Past research has shown the amount of muscle in the body is related to bone growth, but this latest study shows that fat mass is also important in building bone, particularly in girls.
Researchers from Bristol University looked at over 4,000 young people aged 15, using advanced scanning methods which allowed them to measure the shape and density of bones, as well as how much body fat the teenagers had.
Those with higher levels of fat tended to have larger and thicker bones. This was particularly marked in girls, the researchers said.
The results also showed that a 5kg increase in fat mass in girls was associated with an 8% increase in the thickness of the lower leg bone.
As girls tend to have higher levels of fat than boys, even when they are normal weight, the findings suggest fat plays an important role in female bone development.
Building strong bones in youth is particularly important for women, as they are three times more likely to develop osteoporosis, and suffer two to three times more hip fractures than men.
Dr Jon Tobias, who led the research, said: “There is a good deal of pressure on teenage girls to be thin, but they need to be aware that this could endanger their developing skeleton and put them at increased risk of osteoporosis.
“Many people think that exercise is the key to losing weight and building strong bones at the same time – but this may only be true up to a point.
"If you do a good deal of low impact exercise, such as walking, you will certainly lose fat but you may not be able to put enough stress on the bones to build them significantly.
"To offset the detrimental effect of fat loss on your bones, it may be important to include high impact exercise as well, such as running or jumping.”
The research is due to be published in the Journal of Clinical Endocrinology & Metabolism (JCEM)
This article was published on Wed 6 January 2010
Image © Danny Hooks - Fotolia.com
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