Study gives clues to how obesity spreads socially

May 5, 2011, Arizona State University

Obesity is socially contagious, according to research published in the past few years. How it is "caught" from others remains a murky area. But findings from Arizona State University researchers published online May 5 in the American Journal of Public Health shed light on the transmission of obesity among friends and family.

Shared ideas about acceptable weight or play only a minor role in spreading among , according to the findings published in the article "Shared Norms and Their Explanation for the Social Clustering of Obesity."

"Interventions targeted at changing ideas about appropriate body mass indexes or body sizes may be less useful than those working more directly with behaviors, for example, by changing or transforming opportunities for and constraints on ," wrote lead author Daniel J. Hruschka, and co-authors Amber Wutich, Alexandra Brewis and Benjamin Morin, all with ASU's School of and Social Change.

Hruschka and Wutich are cultural anthropologists, while Brewis is a biological anthropologist, and Morin is a graduate student in applied mathematics for the life and social sciences.

"When you see that something like obesity spreads among and , this raises important questions about how it's spreading. Is it because we learn ideas about acceptable body size from our friends and family members, or that we hike together, watch TV together or go out to eat together?" said Hruschka.

"If we can figure out exactly why obesity spreads among friends and family members, that can tell us where to focus resources in curbing rates of obesity. Is it more effective to change people's ideals of acceptable body size in hopes that they will change their behaviors or rather directly target socially shared behaviors that can contribute to or loss?"

To dig deeper into how clustering of body attitudes account for the observed social contagion of obesity in past studies, the ASU team interviewed 101 women from the Phoenix area and 812 of their closest friends and family members.

Comparing the index (BMI) of the women, their friends and family members, the researchers confirmed prior findings that the risk of a woman's obesity rose if her social network was obese.

But the team also examined three potential pathways by which shared ideals of acceptable body size might cause obesity and body size to spread through social ties.

Hruschka explained: "You might learn what is an acceptable body size from your friends and then change your diet and exercise to try to achieve that. Or, you might not agree with what your friends or family members think, but still feel pressure from them to achieve some ideal body size. Finally, you may form an idea of appropriate body size by simply observing your friends' bodies, which in turn changes your eating and exercise habits."

The team discovered no evidence for the first and second pathways as means of transmission and found only limited support for the third, suggesting that other factors such as eating and exercising together may be more important in causing friends to gain and lose weight together.

A strength of the study was the range of approaches taken to assess body size ideals, including ideal body size, anti-obesity preference and anti-fat stigma. For example, the participants were asked to choose whether they would rather be obese or have one of 12 socially stigmatized conditions, such as alcoholism or herpes. In many cases, the women would rather have more of the other conditions, with 25.4 percent preferring severe depression and 14.5 percent preferring total blindness over obesity.

While this study provides some clues, the authors noted that more work needs to be done to assess how other proposed factors, such as shared activities or other kinds of social norms, account for the relationship between social proximity and similarity in BMI.

"This study is important because it shows that while the clustering of people with larger or smaller bodies is real, it is not shared values between friends that accounts for it," said Brewis, director of the Center for Global Health in ASU's College of Liberal Arts and Science. "This gives us important clues about the best ways to tackle obesity as a public health issue; we need to focus on what people do together, rather than what people think."

Related Stories

Recommended for you

Women run faster after taking newly developed supplement, study finds

January 19, 2018
A new study found that women who took a specially prepared blend of minerals and nutrients for a month saw their 3-mile run times drop by almost a minute.

Americans are getting more sleep

January 19, 2018
Although more than one in three Americans still don't get enough sleep, a new analysis shows first signs of success in the fight for more shut eye. According to data from 181,335 respondents aged 15 and older who participated ...

Wine is good for you—to a point

January 18, 2018
The Mediterranean diet has become synonymous with healthy eating, but there's one thing in it that stands out: It's cool to drink wine.

Sleep better, lose weight?

January 17, 2018
(HealthDay)—Sleeplessness could cost you when it's time to stand on your bathroom scale, a new British study suggests.

Who uses phone apps to track sleep habits? Mostly the healthy and wealthy in US

January 16, 2018
The profile of most Americans who use popular mobile phone apps that track sleep habits is that they are relatively affluent, claim to eat well, and say they are in good health, even if some of them tend to smoke.

Improvements in mortality rates are slowed by rise in obesity in the United States

January 15, 2018
With countless medical advances and efforts to curb smoking, one might expect that life expectancy in the United States would improve. Yet according to recent studies, there's been a reduction in the rate of improvement in ...

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

bg1
not rated yet May 05, 2011
Behavior is contagious. People become like the people they're around in ways they're not even conscious of.
dan42day
not rated yet May 06, 2011
If they have established that obesity is somehow spreading in social groups and can't find a psychological reason, have they considered the current speculation that gut micro-organisms could have an influence on body weight?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.