"Most eating disorders start with an attempt to lose weight, typically in 7th or 8th grade," says Mary Beth Kavanagh, an instructor of nutrition at Case Western University. "Rapid weight loss, obsession with food and calories, and cutting out entire food groups can be signs that an eating disorder is developing.
"Parents should carefully monitor their teens' dieting behaviors in a non-invasive way and consult a physician at the first signs of unusual behaviors."
She adds that teens are still building bone mass, and if they abandon certain foods such as dairy products in order to lose weight, they may harm themselves.
"Teens who are overweight should consult with a registered dietitian, perhaps in a group class, in order to monitor intake of important nutrients and the rate of weight loss."
Kavanagh says patients with eating disorders often avoid weighing themselves altogether, as they often have an intense fear of weight gain.
Despite these caveats, Kavanagh argues, "most people can benefit from daily weighing. Weight tends to creep up slowly, and discovering small three- to five-pound gains allows for adjusting eating and exercise behaviors to reverse small gains before they become 20-pound gains, which are harder to reverse."
Despite the findings of the study, there's disagreement among medical experts on the use of the bathroom scale in treating obesity.
Dr. Paul Shekelle, director of the RAND Corporation's Southern California Evidence-Based Practice Center, says that a population-level approach to fighting obesity, rather than one that targets individual patients, will be critical to reversing the trend.
"It's making the stairs easier to take and the elevator harder to take," he says. "It's more public parkways, city redesign."
Shekelle points to interventions that have helped reduce smoking rates, such as raising cigarette taxes, as useful models. "We have to change the social norms in order to have much success."
Based on the results of the new study, he would not recommend that everyone go out and buy a bathroom scale.
"Could [self-weighing] help? Yeah," he says. "Do I think a national public service campaign [trying to convince] everyone to weigh themselves once a day is going to help? No."