Girls who lose weight too much may suffer from osteoporosis

In order to have the so-called perfect size zero body, some teenage girls desperately control their diet, but the size zero body can also put their bones at risk. Their research found that bone strength is related to fat intake. In other words, forcing yourself to lose weight may increase your risk of fractures.

A long-term study of child development shows that fat mass is more important for bone development in girls than in boys.

Researchers have long known that losing weight can cause people to become skinny prematurely, but the latest study finds that losing weight is also a culprit for decreased bone strength.

A research team at a US university studied more than 4,000 15-year-olds, scanning their bones to determine their shape and density, as well as the amount of body fat the participants had. The results found that participants with higher fat mass tended to have stronger bones, and this association was particularly evident in teenage girls. Studies show that for every 11 pounds (5 kg) increase in fat mass in girls, tibia density can increase by 8%.

Even at normal weight, girls have more fat than boys. Studies show that fat plays an important role in women's bone development. Bone mass continues to increase slowly until the mid-twenties, but after the age of thirty-five, bone loss accelerates as a part of the natural aging process.

Building strong bones while young is especially important for women. The reason is that their risk of osteoporosis is three times that of men, and their risk of hip fracture in late life is also three times that of men. Professor Jon Tobias, who led the study, said: "Teenage girls often strive to be thin, but they must realise that being thin puts their bones at risk and increases their risk of osteoporosis."

"Many people think that physical exercise is the key to both losing weight and building strong bones, but it may only work to a certain extent," Tobias said. "If you only do a lot of low-impact exercise, like walking, you can lose fat, but you may not be stressing your bones enough to make them stronger. To compensate for the adverse effects of fat loss on bones, it may be important to also do high-impact exercise, like running or jumping."

Some doctors warned in 2009 that size-zero supermodels not only adversely affect their own fertility and health, but also set a "bad example" for young girls. The latest findings come from a study called "Children of the 90s," which followed 14,000 mothers who became pregnant between 1991 and 1992. The research aims to direct young people and their parents to focus on different aspects of health and behavior.

Other studies have similarly shown that young girls who don't get enough calcium or vitamin D have maximum bone strength that is up to 20% below recommended levels.