Poor Body Image Begets Unhealthy Activity in Teens

MINNEAPOLIS, Aug. 10 -- Teens with a poor body image tend to behave in ways that are self-perpetuating, researchers here said, and may react better to positive encouragement rather than to criticism.

These youths tend to fall into unhealthy and ineffective weight-loss patterns such as fasting, taking diet pills, and inducing vomiting, said Dianne Neumark-Sztainer, Ph.D., M.P.H., R.D., of the University of Minnesota here.

So it's important for parents, teachers, and clinicians not to make teens feel bad about their bodies in hopes of spurring change, Dr. Neumark-Sztainer and colleagues said in the August issue of the Journal of Adolescent Health. That strategy is likely to backfire,

"Our findings indicate that lower levels of body satisfaction are associated with more health-compromising behaviors, such as unhealthy weight control behaviors and binge eating, and fewer health-promoting behaviors, such as physical activity," the authors said.

"These relationships are disturbing, given findings from longitudinal studies showing that dieting, unhealthy weight control behaviors, and binge eating predict weight gain in adolescents," they added.

"Parents, educators, and health care providers should resist utilizing messages aimed at motivating adolescents toward behavioral change via decreasing their comfort with their bodies," they said.

"Instead, it may be more effective to encourage positive change via messages that enhance body satisfaction and a desire to care for one's body," they suggested.

The researchers conducted a five-year longitudinal study of about 2,500 junior and senior high school students in Minnesota, equally divided between the sexes. Participants completed two Project EAT: Eating Among Teens surveys, one in 1999 when they were 13 to 17 years old and one in 2004 when they were 16 to 20 years old.

When ranked into quartiles based on their body satisfaction, nearly 34% of girls were in the lowest satisfaction quartile and about 18% in the highest. For boys the ranking was more even, with about 24% in the lowest quartile and 26% in the highest.

More than 27% of the girls with the poorest body image at the first survey reported inducing vomiting or taking diet pills or laxatives at survey two, compared with less than 20% of the girls with the best body image (P=.029), the study found.

Girls with the most negative body image also reported exercising less than four hours per week at survey two, compared with nearly five hours per week for girls with the most positive body image (P=.034). There was also a non-significant trend toward girls with the worst body image eating fewer daily servings of fruit and vegetables (P=.079).

About 40% of the boys with the most negative body image at survey one reported having fasted, skipped meals, or used a food substitute such as a powdered diet drink at survey two, compared with nearly 27% of boys with the most positive body image (P=.009).

Similarly, 11% of the low-image boys reported binge eating at survey two, compared with 3.4% of the high-image boys (P=.002). (Binge eating was not significantly linked with body image for girls; P=.385.) Body image did not seem to effect how much boys exercised (P=.376) or their fruit and vegetable intake (P=.06)

All of the above results were adjusted for diet and exercise behavior at the time of the first survey and for body-mass index during the study period.

Because of the longitudinal nature of the study, it could not prove a causative link between poor body image and unhealthy behavior, the authors said. A chief weakness of the study was its reliance on self-reports rather than actual measurements or clinical assessments, they added.