Washington: Obesity can be socially contagious depending on the eating and exercising habits of friends and family members.

Researchers from Arizona State University (ASU) interviewed 101 women and 812 of their closest friends and family members exploring three possible ways through which obesity could spread.

The team sought to deduce possible causes of obesity transmission by answering the following questions: Do women decide on "acceptable body size" from friends and change their diet to achieve the weight ideal? Do they feel pressure to conform to a certain size, despite disagreeing with their family's expectations? Or do they form an idea of appropriate body size by simply observing their friends' bodies, and consequently change their eating and exercise habits as well?

Though they found no evidence to support the first two hypotheses and limited evidence to support the third, research suggested other factors like eating and exercising together may be more important in causing friends to gain and lose weight together, they said.

The study was published last week online in the American Journal of Public Health.

"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," said lead author Daniel J Hruschka, a cultural anthropologist. "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 weight gain or loss?"

After comparing the Body Mass 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 also obese.

A 2007 study published in The New England Journal of Medicine found that both obesity and thinness were socially contagious and influenced the social network's body weight: if one person is obese, odds that their friends will also become obese increases by 50 percent, the study found.

Another interesting aspect of the ASU study was that when asked to choose between obesity or a range of 12 socially stigmatized conditions like alcoholism or herpes, many women said they'd take a debilitating condition over being fat. That included 25 percent who said they preferred severe depression and 15 percent opting for total blindness over obesity.

(Courtesy: Mid-day.com)