EPIDEMIC!
You will be fat if friends in your social network are fat. Really?
It seems anecdotal - either completely obvious or an urban myth, but Nicholas Christakis and James Fowler claim to show proof of the pudding in their study, "The Spread of Obesity in a Large Social Network over 32 Years", published in this week's New England Medical Journal (NEJM).
The authors used data from the 'never stops giving' Framington Heart cohort, and importantly "quantified" what many people presumed to be a given, as Christakis explains in this video from Harvard's Office of Public Affairs. Apparently, they conclude, obesity spreads via social clusters which extend to three degrees of separation. Subjects who had a close friend who became obese within a particular time interval increase their own chances of becoming obese by 57%. An obese spouse would increase their chances of becoming obese by 37%, and an obese sibling would increase their chance of obesity by 40%.
Thus, the authors "document" a "higher order effect", "a spreading process through the network", "a cascade", whereby the fat begets fat, a meme perhaps, for those who like memes, or as Christakis put it, "like an epidemic, a real epidemic".
The video backdrop in Christakis's press release is a white board, heartily marked with technical scribblings. Obviously the authors slaved through the night to unveil these exciting results for us. You can make out some of the variables. T is for time I suppose, S - ok, R - sure, F is for..umm...fat? You can't gnash your teeth trying to discern the meaning of these scientific meanderings -- or is that a supply and demand curve? And what's that tic-tac-toe-game to the left of the speaker's head? Christakis helpfully explains all that we the lay audience need to know (except the white board doodles) in this 2 minute and 36 second video.
Genes, Memes, the Environment
It's fashionable these days to let genes off the hook. This study acknowledges genes but targets environmental factors -- sort of. The authors seem to ease by that too. They found that proximity doesn't necessarily influence obesity. If your next door neighbor is obese, this won't influence your own chances of obesity, and thus they say, "local" environment doesn't matter.
"Our findings that the weight gain of immediate neighbors did not affect the chance of weight gain in egos [primary subjects] and that geographic distance did not modify the effect for other types of alters (e.g., friends or siblings) helps rule out common exposure to local environmental factors as an explanation for our observations."
But what might "local" environmental factors of obesity be? Intuitively, we surmise there's nothing unique about Framingham or Massachusetts, obesity-wise. That is there's no rural diet these days that differs significantly from the the urban diet, not Southern diet radically different from a Northern Yankee diet. Sure maybe you can find grits more easily in the South, but local traditions have usually been replaced by not-so-quaint global alternatives.
The old-fashioned soda-fountain has been replaced by McDonald's. Fast-food habits aren't local, nor are habits of allaying thirst with Coca-Cola. Watching TV for 4 hours a day isn't a local habit. Nor is the propensity to drive endlessly around parking lots in a Jeep Patriot or Liberty vying for a parking space less than fifteen paces from the mall entrance.
These not-so-local habits make the jobs of photographers tasked with capturing footage for the ubiquitous evening news about alarming obesity trends easier every day.
It is a "real epidemic", but disease language only gets us so far. Sure it may be interesting to acknowledge that friends and family influence your perception of acceptable weight, as well as what you eat, your religious preferences, voting habits and almost all other choices or beliefs. But does this add meaning to the dilemma or is it just comfort food?
Spend Money, Preserve our Way of Life
In the end, the authors predict that people get fat together, therefore they'll get thin together, although in the study, there was a (to be expected) preponderance of weight gain. A seemingly obvious solution is to dump your fat friends, but the authors say no, no, no! -- don't "get rid of" any friends, since research "suggests" friends are good. What to do then, with this health fad, this obesity meme? As we all know, change is the tough part. We've already errantly tried various flawed experiments to clamp down on the trend.
Cristakis's concludes in his video that "interventions that target groups of individuals rather than sole isolated individuals are likely to be more effective". Aha! Like so many CDC recommendations? Trans-fat legislation? We'll institute more gym. Not possible? Cristakis manages to cover all bets with his third point, hedging, "to the extent that prevention or treatment of weight gain in one person works, you're more likely to contribute to avoidance of weight gain in others." Somehow I sense a collective "PHEW!" from corporations and individuals who would favor this obesity conclusion, this new social network phenomenon, because it requires no policy change.
This is a win, win, win type of study. The media snuggles up to this stuff like cats to catnip despite the very thin veneer of revelation. Weight loss enterprises will smile and thrive on the news. The study won't alarm fast food companies, since it hand waves in other directions. And finally, smart, self-promotional research that it is, presented via video press release, it of course suggests future research. Some scientists fret about the likelihood of not being able to repeat the result, given the uniqueness of the Framingham cohort. But can't intrepid investigators recruit chubby-faced cabals from Facebook to study perhaps? Can't epidemiology take advantage of these free-wheeling information yielding Web 2.0 types? Who needs nurses?
Of course, we've all been holding our breaths, waiting for a breakthrough in the obesity problem. Cristakis adeptly delivers, winding down his 156 seconds by hopefully noting: "the amount of money you spend in helping a person lose weight has much more benefit than you might have imagined". Waddle on then friends, the obesity solution is around the bend, just keep shopping.
(Image source: http://commons.wikimedia.org/wiki/Image:Soda_jerk_NYWTS.jpg)
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Related posts at Acronym Required:
Common Sense Food in Schools
"Why So Fat? It's Systemwide",
"Childhood Obesity, The American Way"
"Survey Says: Pop's Out Drugs are In"
"News of Lightweight Study: 'Obese Should Walk Slowly'"
"Coke: Teaching the World to Sing"
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