We know that poor body image can torment women and girls emotionally, but a new study suggests that it could also cause them to put on weight.
The study, from Norwegian University of Science and Technology, found that teenage girls who are not fat, but feel they are, are more likely to become overweight as adults.
"Perceiving themselves as fat even though they are not may actually cause normal-weight children to become obese as adults," study author Koenraad Cuypers a researcher with the department of public health and general practice in a statement.
The new research, published in the Journal of Obesity, also highlighted how pervasive bad body image is. Nearly a quarter of the normal-weight girls involved in the study felt they were fat.
More than 1,000 healthy-weight teens of both sexes participated in the so-called "Hunt" survey -- a Norwegian study that compiled personal and medical histories collected over two decades. At two different periods in their lives -- when they were between ages 13 and 19, and again when they were between 24 and 30 -- the young men and women answered questions about how they saw their bodies, and researchers recorded their BMI (Body Mass Index), a measurement of weight relative to height.
Around half of the participants were still normal weight as adults, but 38 percent of girls and 50 percent of boys went on to become overweight or obese. (The remaining percentages were classified as underweight; researchers did not focus on them in this study.)
How they felt about their bodies growing up appeared to play a role in their weight later.
Overall, participants of both sexes who felt they were chubby as teens had an average waist circumference around an inch larger than those who saw themselves more positively as they grew up. Nearly 60 percent of girls who felt fat as teens became overweight, based on their BMI.
"It seems paradoxical that [teens] who are more worried about their [body] would end up gaining weight," Dr. C. Barr Taylor, director of the anxiety disorders clinic at Stanford Medical Center and an expert in eating disorders told The Huffington Post.
"But when kids try to start controlling their weight," he said, "some things they think will help, like dieting, are associated with weight gain in the long-run. And some other behaviors, like purging, kids think are going to work, but they don't."
The study authors wrote that teens who see themselves as overweight might start to do things they incorrectly think will help them shed pounds, like skipping breakfast. Many outside studies have found that not eating breakfast can lead to weight gain.
The researchers also suggested that stress that comes with poor body image might lead to belly fat later in life. "A lot less is known about that," Taylor said. "If you start to overvalue weight and shape, you tend to be a little more depressed and in some kids that is tied with overeating. It may be that the effect goes that way, but the data on that is pretty soft."
A notable finding of the new study is how common it was for healthy girls to see themselves as overweight.
Around 1 in 5 girls felt they were fat, compared to just 1 in 11 teenage boys. Taylor said the figures from the Norwegian study are comparable to U.S. estimates.
"In this population, in any ethnic group, we find that at least a quarter [of girls] believe they are overweight," he said. "Kids develop these attitudes very early on -- before age 12 -- and tend to consistently maintain them throughout adulthood."
Cynthia Bulik, director of the University of North Carolina Eating Disorders Program and author of "The Woman In The Mirror" agreed. "There is almost a societal expectation that girls and women be dissatisfied with their weight and shape ... How often do you hear a girl or woman say, 'I like myself just the size I am!"?
A 2010 survey conducted by the Girl Scout Research Institute found that nearly 9 in 10 girls between 13 and 17 felt pressure to be thin from the fashion industry and media, and nearly 1 in 3 admitted to starving themselves in order to lose weight.
According to the study's authors, school-based interventions that show a broad-range of beautiful bodies can help combat those pressures. In a statement, Cuypers said that "the media must cease to emphasize the supermodel body as the perfect ideal, because it is not."
Taylor agreed that school programs can make a difference, particularly if enough students in a particular school "buy into" a program. But he said that helping teenage girls feel better about their bodies is an uphill battle.
"It is complicated and difficult, not because we don't know what to do, but because our culture so overvalues thinness that it makes messages that go the other way very difficult to hear," he said.