If you think America's obesity epidemic will pass you by because you are young and fit now, think again. In the past 30 years, the portion of the population that is obese has risen from 15 percent to 33 percent. Now the Centers for Disease Control and Prevention predicts that more than 42 percent of people will be obese by 2030 – not just overweight, but clinically obese, with a body mass index of more than 30. (A healthy BMI for men is around 19 or 20.) And scientists can only speculate about the percentage of people who will be overweight.
This new statistic, while frightening, isn't a surprise to obesity experts who have watched and forecasted America's growing levels of fatness for decades. And now experts are scrambling to understand why. Most blame the epidemic on a variety of factors that can include everything from more chemicals in personal-care products, furniture, and food to the lack of sidewalks on city streets and a proliferation of elevators in buildings. Among many leading authorities, a contentious debate exists over whether it's the calories or the carbs in food that cause people, including those who work out every day, to pack on the pounds. Here, we examine five different perspectives from some of the country's leading obesity experts.
It's sugar, stupid.
Science journalist, author, and theory maverick
Gary Taubes believed something was missing from the "calories in-calories out" theory in the 1990s, when the former Harvard defensive lineman was watching his diet, working out an hour a day, and still gaining weight. That's when he figured he'd try "this crazy Atkins thing," which melted the weight off and set him on a mission to figure out why. The yield to date: two rigorously argued books, 'Good Calories, Bad Calories' and 'Why We Get Fat,' which challenged the scientific orthodoxy of the obesity epidemic and caused many leading researchers to reconsider the evidence.
In Taubes' view, the rise in obesity comes from our dietary overload of carbs once the public-health establishment declared fat evil and grains good. It comes down to Adiposity 101: Eating too much sugar stimulates the hormone insulin, while fat and protein do not. Increased insulin triggers hunger and causes calories not immediately burned to be stored as fat. This theory was vindicated by a recent study that found that low-carb, low-sugar diets increase metabolism and weight loss more than low-fat diets with the same number of calories.
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The journalist has joined forces with Dr. Peter Attia to launch the Nutrition Science Initiative nonprofit, which will do the research that Taubes hopes will prove the obesity epidemic comes down to a sugar-insulin cycle. "My dream is that you go to the doctor and he says, 'You're 10, 20 pounds overweight and getting fatter. Boom – don't eat these foods.'"