Why are so many of us carrying so much extra baggage? It’s a question that has, ahem, weighed heavily on researchers ever since obesity rates started swelling in the 1980s.
The chunk of the U.S. adult population classified as obese — defined as having a body mass index of 30 or higher — has roughly doubled, to more than 38 percent, in the last three decades. The cause, according to the most consistent research results, is relatively simple: overeating.
Scientists and snake oil salesmen alike have continued to offer alternative explanations for our collective weight gain. Among the more credible contenders: sugar, hormones and even the microbiome, the personal ecosystem each of us hosts. All of these hypotheses have advocates as well as critics. Both sides of each argument can offer evidence in support of their claim. The research community has built a large body of inconclusive, contradictory research. What they haven’t built is consensus.
“It’s the Wild, Wild West of opinion,” says Dariush Mozaffarian, a cardiologist and dean of the Friedman School of Nutrition Science and Policy at Tufts University.
But maybe that body of conflicting, equivocal evidence does tell us something. If there were no particular food — or component of food, or combination of foods, or virus, or habit, or assortment of gut bacteria — wreaking biochemical havoc, inconclusive research would be exactly what we’d expect to see.
