Teenage girls who diet are far more likely to go partying, smoke and binge-drink.
Scientists discovered that girls who were dieting were far more likely to drink, smoke and skip breakfast than those that were not watching what they were eating.
A study by the University of Waterloo also found dieters were 1.6 times more likely to smoke and skip breakfast, and 1.5 times more likely to smoke and get wasted on booze.
Study lead Amanda Raffoul, a PhD candidate in Public Health and Health Systems, said: "It might seem natural for there to be a connection between dieting and behaviours such as smoking and skipping meals, but the explanation is not so clear for something like binge drinking.
"Our findings suggest that dieting and other risky health behaviours may be related to common underlying factors, such as poor body image.
"The link between dieting and other health-compromising behaviours is worrisome since 70 percent of girls reported dieting at some point over the three years.
"Post-puberty changes often lead to weight gain among girls and there is incredible pressure from social media and elsewhere to obtain and maintain the ideal body."
She added that weight loss should not be encouraged for teenage girls as they are at a higher risk of developing eating disorders.
She added: "Intentional weight loss is not something we should necessarily encourage, especially among this population, since it's possible that well-meaning initiatives that promote dieting may be doing more harm than good.
"Instead, we should focus on health broadly rather than weight as an indicator of health."
The researchers examined data from more than 3,300 high school girls in Ontario, Canada, who participated in a longitudinal school-based study called COMPASS.
The study was published in the Canadian Journal of Public Health.