A recent study published in the New England Journal of Medicine found that “obesity appears to spread through social ties,” suggesting that the condition, which afflicts over 30 percent of the U.S. population, moves in a manner not unlike an infectious disease. Indeed, news headlines used the word “contagious” to describe the epidemic, indicating that fatness could migrate through social networks “like a virus.”
Fat Friend = Fat You?
But just how does this work? The authors speculate that having obese social contacts could increase a person’s “tolerance” for obesity (if everyone around you is big, it doesn’t seem abnormal) or might influence their adoption of certain behaviors (getting super nachos instead of a salad). Having an obese friend was found to increase a person’s risk of becoming obese by 50 percent; having an obese sibling increased the risk by 40 percent, and an obese spouse by 37 percent.
This is not groundbreaking news, as any woman who has tried to go head-to-head at the dinner table with a metabolically advanced beau knows. But I was disturbed by the news coverage of the study, which seemed to indicate that befriending a thin person might make you thin, or that having fat friend was the “cause” of someone’s own obesity.
Because, if the obesity all started with one fat friend, how did he or she get “sick” in the first place?
Running from Woolly Mammoths Influenced Our Genetics
Many people point to genetics as one cause for obesity, but our genetic make-up has not changed that dramatically—if at all—since the seventies, when there was no epidemic. What is in our all of our genes, however, is the penchant to overeat fatty foods. This is a relic of harder times, when food was not as abundant as it is today. Our genetic taste buds made energy dense food desirable because it was necessary to pack away calories so we could make it through the thin times. We feasted when we could, in preparation for the famine.
However, this system has gone seriously awry in a super-sized environment. We are still programmed to finish our plates, but unfortunately, our plates have gotten much, much bigger.
Consider a cup of coffee. Twenty years ago, the standard size was eight ounces; nowadays it is about twice that. A Starbucks venti is the size of my forearm. Grabbing a couple of slices of pizza with a friend used to mean about five hundred calories, now it’s more like nine hundred. This change in portion size coincides nicely with our own expanding muffin tops, and the NEJM study, which followed the weight and social networking patterns of study participants over the past thirty-two years.
Not only are we used to getting more burger for our buck, we don’t have to go very far to get it. Junk food is cheap and readily accessible, and can be found everywhere from high schools to hospitals. On a road trip with friends, it’s easy to find yourself in a fast food restaurant, not because the hefty person made your collective decision, but because healthful options are few and far between. This, combined with pervasive food advertising, is constant encouragement to consume more food, more often.
If only we were still running from woolly mammoths, perhaps we could sit down, eat a three-tiered hamburger with fries and forty ounces of cola, and maintain a normal weight. But between the car and the cubicle, the only time many of us move our fast-twitch muscles is on the freeway.
Our Genetics Can't Change, but Our Environment Can
Of course, these societal influences do not exonerate our friends, or us. The people we enjoy spending time with are the ones we often eat with, so it makes sense that how and what they eat is likely to influence our own behavior. If your friend starts to look a little pudgy, it may help justify your own weight gain; if a friend orders a side salad with sparkling water, you may feel guilty about getting the burger and milkshake. And friends aren’t exactly shoving food down each other’s mouths; it’s up to the individual to show a little self-constraint.
But the trend towards obesity is bigger than the individual. Media, industry, and the government play a role in creating what is acceptable and available. As with smoking, it used to be normal for people to puff away in restaurants and in the office, or to see pregnant women with cigarettes. Though these were individual behaviors making it collectively okay to smoke, it was part of an atmosphere of acceptance largely promoted and cultivated by the tobacco industry. Our greatest sustainable gains, therefore, came from broad environmental changes—advertising bans, tax increases, clean indoor air laws—that helped change societal norms, discouraging people from smoking in the first place. Rather than targeting individuals, preventing obesity will require similar societal changes, many of which are already starting to be made, such as increasing availability of fruits and vegetables, “smart” urban design, and restricting junk food advertising geared toward kids.
Having an obese friend is no more likely to “make” you obese than having a thin friend will “make” you thin (unfortunately). Association is not causation, as the epidemiologist well knows. Unlike removing an infected water source to get rid of the origin of a cholera outbreak, removing an obese person from a social network will not remove the origin of obesity from our society. Our genetic predisposition is difficult, if not impossible, to change, but our overabundant environment is not.
Updated August 15, 2008
Related Article: How to Choose Your Food: Nourishing Thoughts