"Dieting was a significant predictor of initiation of regular smoking among females," said Dr. Mildred Maldonado-Molina, assistant professor of epidemiology and health policy research, and lead author of the study published in the American Journal of Health Promotion.
"We were expecting that this relationship was going to be stronger among females. That has been well-documented, especially because (nicotine) can suppress your appetite," she said.
The study also showed that boys who did on and off dieting were more likely to engage in smoking behaviours.
"In boys we found something we don't understand yet. We found that those who were inactive dieters, those who first started dieting and then stopped, were more likely to engage in smoking behaviours," said Dr. Maldonado-Molina.
The researchers based their findings on the replies of 7,795 adolescents surveyed during the first two waves of the National Longitudinal Study of Adolescent Health, completed in 1994 and 1996. The teens were in seventh, eighth and ninth grade at that time.
Adolescents who said they were trying to lose weight were divided into four groups—new dieters, non-dieters, former dieters and consistent dieters, who said they were dieting both times. The researchers excluded teens who were already smokers, and those who admitted to taking diet pills, vomiting and using other unhealthy weight-loss tactics.
"That group (of teens who were beginning to diet) was the one we were most interested in, seeing how the start of one behaviour related to initiation of smoking," Dr. Maldonado-Molina said.
The study showed that girls who consistently dieted were more likely to smoke.
Dr. Maldonado-Molina said that smoking to suppress the appetite might be one reason why some dieting teens picked up the habit.
She, however, said that parents should not go on red alert if their children started dieting, for some dieting practices like eating balanced meals could be a part of a healthy lifestyle.
"This doesn't mean if your child starts dieting they are going to start smoking. I think (parents should) be vigilant and talk about it. It's looking for those changes in behaviour," she said.