http://www.abc.net.au/news/stories/2007/07/26/1988616.htm
Quote:
Obesity contagious among friends, US study shows
By North America correspondent Kim Landers
The United States is often tagged with the dubious reputation of being the most overweight country in the world. Now a new study shows that obesity is contagious and that it is actually people's friends who are helping to make them fat.
Over the last 25 years, obesity among American adults has more than doubled, with a third of people now considered extremely overweight. Obesity is at record levels in the US, and some researchers call it an epidemic.
While factors like poor diet and lack of exercise certainly contribute, for the first time research shows obesity is actually contagious, spreading from one friend to another.
Study co-author James Fowler is an associate professor of political science at the University of California in San Diego.
"A person's chances of becoming obese increase by 57 per cent if they have a friend who becomes obese," he said.
"Similarly, a person's chances of becoming obese increase by 40 per cent if they have a sibling who becomes obese.
"A person's chances of becoming obese increase by 37 per cent if a spouse becomes obese."
In medical terms, being obese means having a body mass index greater than 30.
Dr Fowler says his study shows siblings, spouses and neighbours have less influence than friends when people decide how much to eat, how much to exercise and how much weight is too much to put on.
"Friends who are hundreds of miles away have just as much impact on a person's weight status as friends who are right next door," he said.
"So what this suggests is that it's not the case that this causal relationship is due to people eating together or exercising together; rather, it has to do with them sharing ideas about what healthy behaviour is like."
The study was done in conjunction with Harvard Medical School.
Researchers analysed data taken over 32 years for more than 12,000 adults who were already part of the Framingham Heart Study.
Dr Matthew Gillman is the director of the Obesity Prevention Program at Harvard Medical School.
"While genes can certainly affect whether one individual is obese compared with another, genes can't really explain the obesity epidemic, which is a phenomenon of the last 30 years," he said.
The spread of obesity through social ties could have important implications for how public health officials tackle the epidemic.
Dr Richard Suzman is the director of the Behavioural and Social Research Program at the National Institute on Ageing.
"I think what this also does is that it takes what was seen as a non-infectious or non-contagious or non-communicable disease and shows that it's clearly got communicable factors," he said.
If the current weight gains continue, 41 per cent of Americans will be obese by 2015. If nothing is done, obesity will soon become the leading preventable cause of death in the United States.
This day will mark a firm dividing line in time. From this day on, fat people will be made outcast and feared as the modern lepers of society lest they pass on their deadly contagion to all healthy people.