OTHERWISE healthy teenage girls who diet regularly show worrying signs of malnutrition, Sydney researchers have found. The largest study of its kind shows pressure to be thin could be causing teenage girls serious harm, potentially preventing them from developing properly. The study of 480 girls, between 14 and 17, attending school in Sydney’s northern suburbs and on the central coast, found those who dieted often showed subtle but chronic signs of undernourishment compared to those who occasionally, or never, dieted. The girls were deficient in a number of nutrients and biochemicals, including calcium and protein, as well as haemoglobin, which is vital for transporting oxygen in the blood.
The study leader, Dr Ross Grant, said the teenagers were not getting the nutrients they needed to build their bodies. ”When you get through your adolescent years you should be the healthiest you are ever going to be, and these girls are not giving themselves the best chance to be healthy,” he said. Many students in the study were dieting even though, on average, they were not overweight. ”These are pretty much your average girls on the north shore. They are going to school and they are not unwell in any other way,” Dr Grant said. The low levels of calcium were particularly worrying, he said. ”Calcium is used as a signalling molecule for every cell in the body. If you are not getting enough calcium in your diet then your body starts to get it from wherever it can, which is the bones.”
Most researchers believe the amount of calcium consumed in a person’s teenage years sets the basic level available for the rest of their life. Media messages presenting excessively thin women as having an ideal body shape, or public health campaigns making girls overly aware of not consuming too many calories, could be to blame for dieting, said Dr Grant, who is the head of the Australasian Research Institute at the Sydney Adventist Hospital.
Christine Morgan, the chief executive of the Butterfly Foundation, an eating disorders advocacy group, said she was horrified, but not surprised, by the findings. ”Diets, by their very nature, are telling you to disregard your physiological appetite,” she said. ”These homespun diets result in us not putting the nutrients we need into our bodies.” Disordered eating – irregular eating behaviours that do not fall into the category of an eating disorder – had more than doubled in the past 10 years. ”It has become the norm,” Ms Morgan said.