Americans are caught in a contradictory cultural schism. If a girl is thin, parents feel like they need to have an intervention. But we are in a war on obese people and politicians are responding to that by banning everything that looks like it can pass the legislature. Pressure to be thin may be making girls fat - except in Europe, where impossibly attractive naked women are on public billboards.

Are Americans so fat because of too much pressure to be thin?

A JAMA Pediatrics paper believes so, and finds that girls who are told by a parent, sibling, friend, classmate or teacher that they are too fat at age 10 made them more likely to be obese at age 19. Meanwhile, every epidemiology study being done shows that the rampant obesity in young people can only be halted by implementing stricter diet choices. How do you change a child's diet without implying they are fat?

The psychologists looked at 1,213 African-American girls and 1,166 white girls living in Northern California, Cincinnati and Washington, D.C., 58 percent of whom said they had been told they were too fat at age 10. All the girls had their height and weight measured at the beginning of the study and again after nine years.

Overall, the girls labeled fat were 1.66 times more likely than the other girls to be obese at 19, the researchers found. They also found that as the number people who told a girl she was fat increased, so did the likelihood that she would be obese nine years later. 

"Simply being labeled as too fat has a measurable effect almost a decade later. We nearly fell off our chairs when we discovered this," said A. Janet Tomiyama, an assistant professor of psychology at UCLA, the study's senior author. "Even after we statistically removed the effects of their actual weight, their income, their race and when they reached puberty, the effect remained. That means it's not just that heavier girls are called too fat and are still heavy years later; being labeled as too fat is creating an additional likelihood of being obese."

Co-author Jeffrey Hunger, a graduate student at UC Santa Barbara, said that simply being called fat may lead to behaviors that later result in obesity.

"Being labeled as too fat may lead people to worry about personally experiencing the stigma and discrimination faced by overweight individuals, and recent research suggests that experiencing or anticipating weight stigma increases stress and can lead to overeating," he said.

No connection between dieting and improvements in health

In a separate paper published last December, Tomiyama, former UCLA psychology faculty member Traci Mann (now at the University of Minnesota–Minneapolis) and UCLA graduate student Britt Ahlstrom analyzed 21 long-term studies on weight loss and health and found no clear relationship between weight loss and health improvements related to hypertension, diabetes, cholesterol and blood glucose.

"We found no connection whatsoever between the amount of weight loss — whether small or large — and any of these health outcomes," said Tomiyama of the study, which appeared in the health section of the journal, Social and Personality Psychology Compass.

"Everyone assumes that the more weight you lose, the healthier you are, but the lowest rates of mortality are actually in people who are overweight," she said. "At a body mass index of 30, which is labeled obese, there is no increased risk of mortality. This has now been shown over and over again. The highest rate of mortality is in the underweight people."

The research findings also confirmed the results of a 2007 study in which Tomiyama, Mann and colleagues analyzed 31 long-term studies and found that people can initially lose 5 to 10 percent of their weight on any number of diets, but the majority regain all the weight, plus more. Only a small minority, they discovered, sustain their weight loss.

"Eating in moderation is a good idea for everybody, and so is regular exercise," Mann said at the time of the initial study.

"If dieting worked, it wouldn't be a $60 billion dollar industry," said Tomiyama, who noted that trying to be thin is similar to trying to be taller.

"The genetic power over weight is about the same as the power of genes over your height," she said. "People who say it's your fault if you're fat underappreciate the role of genes."

Research has shown that twins separated at birth have very similar weights, regardless of the environment in which they grow up, Tomiyama noted. She recommends focusing on eating healthier and fitness rather than obsessing about weight and strongly opposes stigmatizing people who are overweight.

"When people feel bad, they tend to eat more, not decide to diet or take a jog," she said. "Making people feel bad about their weight could increase their levels of the hormone cortisol, which generally leads to weight gain."

The data used in the study came from the National Heart, Lung and Blood Institute.