Teen girls who start dieting twice as likely to smoke.

Adolescent girls who begin dieting are twice as likely to begin smoking cigarettes regularly, according to a longitudinal study.

Among teenage boys, on the other hand, inactive dieters are significantly more likely to begin regular smoking, according to the study by Mildred M. Maldonado-Molina, Ph.D., of the University of Florida, Gainesville, and her colleagues (Am. J. Health Promot. 2007;22:25-32).

"It is important to consider dieting and its relation with other risk-taking behaviors in adolescents, such as smoking," the investigators wrote. "Studies targeting the prevention and reduction of smoking ... [also] need to acknowledge the initiation of dieting practices, the incidence of dieting and smoking during the same period of time, and how these two behaviors vary by gender."

The study involved a subanalysis of data from the National Longitudinal Study of Adolescent Health, a school-based study of the health-related behaviors of adolescents in grades 7-12. A total of 9,632 students were interviewed between April 1994 and December 1995, and then reinterviewed a year later. Their mean age was 15.2 years at the first interview.

Investigators excluded 1,837 students who reported having already tried cigarettes regularly at the first interview, leaving 7,795 non-Hispanic whites and non-Hispanic blacks as the study population. The investigators excluded Hispanic students because of previous research indicating that smoking behaviors differ by ethnicity, and because the term "Hispanic" is broad, comprising several distinct ethnicities.

Of the students included in the study, 3,522 reported having tried cigarettes (although not regularly) at the first interview. These students were excluded from analyses of trying smoking but not from analyses of initiating regular smoking, which the investigators defined as at least one cigarette per day for 30 days.

Girls had a much higher prevalence of dieting than boys, 55% vs. 25%. After controlling for several covariates such as age, ethnicity, overweight, false perception about weight, and availability of cigarettes in the home, the investigators found several other important differences between boys and girls.

Among girls there was no significant association between dieting status or other covariates and trying smoking, but among boys those who were not overweight and those who had cigarettes available to them at home were both about 50% more likely to try smoking.

There were significant associations between dieting status and the initiation of regular smoking in both genders. Among girls, whites were three times as likely to begin regular smoking as blacks, those with cigarettes available in the home were 55% more likely to begin regular smoking than those without availability, and those who initiated dieting (that is, those who reported not dieting at the first interview but reported that they were at the second) were 94% more likely to start regular smoking than nondieters.

Among boys, whites were 74% more likely to begin regular smoking than blacks, those with cigarettes available in the home were 39% more likely to begin regular smoking than those without availability, and inactive dieters (those who reported dieting at the first interview but not the second) were 74% more likely to begin regular smoking than nondieters.

The study was supported by the National Institute on Drug Abuse. Investigators reported no conflicts of interest.

BY ROBERT FINN 

San Francisco Bureau