WASHINGTON: A new study has shed light on the prevalence of eating disorders amongst adolescents of various ethnic groups by finding that male adolescents are at an increased risk of developing eating disorder symptoms.

The research also found that black females are least likely to practice weight control.

The study, one of the first to examine trends in adolescent weight control behaviours over a 10-year period, found that the incidence of these behaviours in male adolescents significantly increased, while black females appear to resist pressure to pursue thinness.

Led by Y May Chao of Wesleyan University in Middletown, CT, researchers examined data from nationally representative samples of high school students from 1995 to 2005. The data was available via the Youth Risk Behaviour Surveillance System (YRBSS), a survey conducted every two years since 1991 by the Centers for Disease Control and Prevention to assess the prevalence of health-risk behaviours among teens.

The results showed that the prevalence of dieting and diet product use among female adolescents significantly increased between 1995 and 2005 and as did the prevalence of all weight control behaviours (including dieting, diet product use, purging, exercise and vigorous exercise) among males.

The data suggested that black female adolescents are the least likely to practice weight control, while white female adolescents are the most likely. Among males, white adolescents are the least likely to practice weight control and Hispanic adolescents are the most likely.

The authors suggest that Hispanics may be more motivated to control their weight due to the higher prevalence of overweight among these young men.

The increase in weight control behaviours among males indicates that the social pressure for men to achieve unrealistic body ideals is growing, putting young males at an increased risk of body dissatisfaction and developing an eating disorder, according to the authors.

"Considering that males have negative attitudes toward treatment-seeking and are less likely than females to seek treatment, efforts should be made to increase awareness of eating disorder symptomatology in male adolescents, and future prevention efforts should target male as well as female adolescents," the authors said.

The study reported the 10-year trends but also showed that some behaviours fluctuated during this period. The authors propose that some practices, such as dieting, may be sensitive to changes in certain aspects of culture, such as fashion and topics of media focus, or seasonal variations, since it was not known at what time of year the YRBSS was administered.

Surprisingly, unlike previous studies, the current study did not find that ethnic differences in weight control behaviour are decreasing. The authors say that black women tend to have more flexible concepts of beauty, which may make them less vulnerable to social pressure.

However, this may put them at increased risk for becoming overweight, given the current environment of super-sized portions of nutritionally deficient foods, the add.

"Males, especially ethnic minority males, are under studied in this field, and this study provides key information about the prevalence of weight control practices in a large, diverse sample of male adolescents and raises important questions about the factors contributing to the ethnic difference in weight control practices among male adolescents," they conclude.

The study is published online in the International Journal of Eating Disorders, the official journal of the Academy for Eating Disorders.