Girls on 'size zero' diets put bones at risk
Published 06/01/2010 | 05:00
TEENAGE girls dieting to reach size zero may be putting their bones at risk of long-term problems such as osteoporosis, a new study has revealed.
Findings from the 'Children of the 90s' project, which has followed a group of children for nearly two decades, shows that fat mass plays an important role in building bone, particularly in girls.
The researchers, from Bristol University, looked at more than 4,000 young people aged 15, using scanning techniques that calculated the shape and density of their bones, as well as how much body fat they had. Those with higher levels of fat tended to have larger and thicker bones.
In girls, a 5kg increase in fat mass was associated with an 8pc increase in the circumference of the tibia (lower leg bone). As girls tend to have higher levels of fat than boys, even when they are of normal weight, the findings suggest that fat plays an important role in female bone development, with the positive influence about 70pc greater in girls.
Recent research by the Eating Disorders Research Unit at King's College London found that constant images of stick-thin, size-zero models, pop stars and actresses is fuelling a rise in eating disorders.
Evidence from 25 research studies showed that this effect was strongest in adolescents.
Professor Jon Tobias, leader of the research, said the findings suggested that excessive reduction in fat mass could have adverse effects on the developing skeleton and longer-term bone health.
"There is a lot of pressure on teenage girls to be thin, but they need to be aware that it could endanger their developing skeleton and put them at increased risk of osteoporosis," he said.
"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." (© The Times, London)