A recent study by Yale’s Rudd Center for Food Policy and Obesity shows that many anti-obesity campaigns might be stigmatizing obese people instead of encouraging healthier behaviors.

The study, published in this month’s issue of the International Journal of Obesity, found that people are more likely to change their habits in response to advertisements promoting specific behaviors than to those that blame obese individuals for their weight. Rebecca Puhl, director of research at the Rudd Center and lead author of the study, said she hopes it will highlight the need for more research to evaluate the effectiveness of anti-obesity initiatives.

The research team took a random sample of 30 visible anti-obesity campaigns and surveyed over 1,000 subjects on their attitudes towards the campaigns. Participants were shown 10 of the ads at random and then asked to rate how accurately characteristics such as “motivating, stigmatizing or vague” applied to the ads. They were also asked to what extent they would change their health behavior based on the advertisement.

According to the study, campaigns that did not mention obesity at all were the most effective. Those that were rated as more stigmatizing were also the least effective at changing behaviors.

“Messages that emphasized specific health actions that people could take like daily physical activity or eating more fruits and vegetables — messages like Michelle Obama’s Let’s Move campaign and the Five-a-Day campaign — were rated the most motivating and least stigmatizing,” Puhl said.

Bryn Austin, professor of health communications at the Harvard School of Public Health, said the study was excellent in its methodology and analysis. She cited the range of different types of campaigns and the national sampling design as strong elements of the study’s approach.

“There’s a belief that we need messages that ‘wake people up’ or that shock people, but what this study shows and what we know from health communication literature is that convincing people that obesity is real is not the problem,” Austin said.

Instead, she said campaigns should offer something concrete, like reducing sugar consumption, and to encourage strength.

Puhl said she would like to see anti-obesity marketing focus on health instead of weight.

“We don’t even need to mention the words ‘body weight,’ ” she said.

Austin said that one of the most off-putting ads used in the study was the controversial campaign launched by Children’s Health Care of Atlanta, which features billboards with overweight youth and captions like “Being fat takes the fun out of being a kid.”

Timothy Edgar, graduate director in health communication at Emerson College, said the study’s conclusion that people are best motivated by messages that instill them with a sense of confidence should discourage such stigmatizing advertisements.

“I hope that groups such as Children’s Health Care of Atlanta stop wasting valuable resources on initiatives that defy research on how to most effectively change behavior,” Edgar said.

According to Puhl, this study came at a crucial time, because the number of anti-obesity campaigns is rapidly increasing without anyone measuring their effectiveness.

Puhl added that, without research into these campaigns’ effects, they could accidentally stigmatize obese populations without supporting changes in behavior.

“To our knowledge this is the first research to systematically access public obesity campaigns,” Puhl said. “It’s seen with other health conditions like AIDS, but never with the obesity issue.”

The Rudd Center was founded in 2005 by psychology professor Kelly Brownell, who still serves as its director today.