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.
