THE BLOG
01/06/2015 01:24 pm ET Updated Mar 08, 2015

Is Obesity a Self-Fulfilling Prophecy?

PhotoAlto/Laurence Mouton via Getty Images

There are lots of people of normal, healthy weight who, when they look in the mirror, see a fat person. Many of them know that their perceptions are skewed, because trusted friends and family have testified that they are slender, yet they can't deny what they see in their reflection and mind's eye.

Such distorted perception is especially common among teenagers, and it has been linked to poor self-esteem and eating disorders. Adolescents who see themselves as overweight are more likely to use diet pills, laxatives, vomiting and extreme dieting to lose their imagined weight. Paradoxically, these teenagers exercise more than most, but they are also more prone to overeating, often while parked in front of the TV.

But do these teenagers actually grow up to be obese adults? The transition from adolescence to adulthood is a critical time for the development of obesity, but surprisingly, such teenage misperception has not been explored as a risk factor for obesity later on.

Until now. Florida State University psychological scientists Angelina Sutin and Antonio Terracciano wondered if this kind of misperception -- and the self-stigmatization that accompanies it -- might increase the likelihood of being obese in adulthood. In other words, do some teens, because they embody the caricature of a fat person, literally grow into that caricature?

Sutin and Terracciano investigated this intriguing idea by using existing data from the National Longitudinal Study of Adolescent Health. They selected more than 6,000 subjects who had been normal weight -- as measured by their Body Mass Index -- when they were about 16 years old. Some of these teens had perceived their weight accurately at that time, while others had wrongly viewed themselves as heavy. They also gathered information about these subjects 12 years later, when they were about 28 years old.

They crunched the data to see if those with distorted perceptions of themselves actually became obese at age 28. And they did, clearly: As reported in a forthcoming issue of the journal Psychological Science, the fit teens who saw themselves as fat had a whopping 40 percent greater risk of being obese at 28, compared to fit teens with accurate perceptions. Although this risk was apparent for both sexes, it was much greater for males. Indeed, misperceived overweight was associated with an 89 percent increased risk of obesity for boys, compared to a 29 percent increase among girls. This is a surprising finding, since boys are not traditionally considered high risk for distorted body weight perceptions. Distorted perceptions were unrelated to any risk of being underweight.

So what's the psychological link between distorted perception and obesity? Since teenagers who see themselves as fat are more prone to extreme dieting practices, these behaviors are one likely culprit linking misperceptions and later obesity. But it is also possible that stigma plays a role. It's known that teenage girls who are labeled fat by others are more prone to binge eating and other behaviors that cause obesity. These findings suggest that self-stigmatization may work the same way, the scientists say. Teenagers with distorted perceptions may internalize weight biases, which in turn trigger obesity-related behaviors.

It's also possible that misperceived weight may be linked to diminished self-control. That is, teens who internalize society's weight bias may experience more anxiety and depression and less sense of control, which in turn may lead to emotional eating and problems with restraint. So in a self-fulfilling prophecy, teens who see a fat person in the mirror may be less able to maintain a healthy weight: As they gain weight in young adulthood, they are simply becoming the fat person they long perceived themselves to be.

Follow Wray Herbert's reporting on psychological science in The Huffington Post and on Twitter at @wrayherbert.