Teenage girls who diet to reach a 'fashionable' size zero may be seriously harming their health.

Researchers at Bristol University measured the density, bone shape and body fat of 4,000 15 year old girls. The findings show that those girls with higher levels of body fat have denser bones. This leads to the suggestion that those girls seeking a size zero through deiting and weight loss may carry a higher risk of developing long term bone issues, including osteoporosis, than girls who carry more body fat in the early and mid-teens.

Women are 3 times more likely to develop osteoporosis later in life than men. Therefore is is paramount that women develop stronger denser bones in their teens and early womanhood.

Another key factor to developing strong dense bones is exercise. However, researchers believe that low-impact exercise like walking, whilst helps to burn body fat and aid weight loss, doesn'ts place bones under sufficient stress to cause them to adpat and become stronger.

Many factors contribute to the density of bones, including:

• Genes
• Calcuim consumption and absorption
• High impact activities and weight bearing exercise

The Bristol study also suggests that body fat levels in teens also plays a part in developing strong bones in females, with the study showing higher body fat levels positively increased the bone density of girls.