without attempting to explain how these two notions can be reconciled. This situation is not improved by the prevailing attitude of many nutritionists, obesity researchers, and public-health authorities that it is evidence of untoward skepticism to raise such issues, or to ask questions that lead others into contemplating the contradictions themselves.
For the past decade, public-health authorities have tried to explain the obesity epidemic in the United States and elsewhere. In 1960, government researchers began surveying Americans about their health and nutrition status. The first of these surveys was known as the National Health Examination Survey. It was followed by an ongoing series of National Health and Nutrition Examination Surveys (NHANES), of which there have been four so far. According to these surveys, through the 1960s and early 1970s, 12–14 percent of Americans were obese. This figure rose by 8 percent in the 1980s and early 1990s, and another 10 percent by the turn of this century.
This doubling of the
Some factor of diet and/or lifestyle must be driving weight upward, because human biology and our underlying genetic code cannot change in such a short time. The standard explanation is that in the 1970s we began consuming more calories than we expended and so as a society we began getting fatter, and this tendency has been particularly exacerbated since the early 1980s.
Authorities phrase this concept differently, but the idea is invariably the same. The psychologist Kelly Brownell, director of the Yale Center for Eating and Weight Disorders, coined the term “toxic environment” to describe an American culture “that encourages overeating and physical inactivity” and so encourages obesity as a consequence. “Cheeseburgers and french fries, drive-in windows and supersizes, soft drinks and candy, potato chips and cheese curls, once unusual, are as much our background as trees, grass, and clouds,” says Brownell. “Few children walk or bike to school; there is little physical education; computers, video games, and televisions keep children inside and inactive; and parents are reluctant to let children roam free to play.” In an editorial entitled “The Ironic Politics of Obesity” published by
SOURCE: Centers for Disease Control and Prevention, National Center for Health Statistics,
More than one billion adults worldwide are overweight, according to the World Health Organization; three hundred million are obese and obesity rates have “risen three-fold or more since 1980 in some areas of North America, the United Kingdom, Eastern Europe, the Middle East, the Pacific Islands, Australasia and China.” In these regions, too, prosperity is seen as the problem. “As incomes rise and populations become more urban,” the WHO said, “diets high in complex carbohydrates give way to more varied diets with a higher proportion of fats, saturated fats and sugars. At the same time, large shifts towards less physically demanding work have been observed worldwide. Moves towards less physical activity are also found in the increasing use of automated transport, technology in the home, and more passive leisure pursuits.”
It all sounds reasonable, but there are so many other variables, so many other possibilities—including the fact that the consumption of refined carbohydrates and sugars has also been increasing dramatically. To determine which hypothesis is most likely to be correct, it’s useful to focus on the United States, because it offers a starting point for the epidemic—between the late 1970s and mid-1980s*66 —and resonably consistent data with which to work.
The question of how much we eat, whether in a population or as an individual, is difficult to assess, but the evidence suggests that we consumed more calories on average in the 1990s than we did in the 1970s. According to NHANES, American men increased their calorie consumption from 1971 to 2000 by an average of 150 calories per day, while women increased their consumption by over 350 calories. This increase in energy intake, according to a 2004 report published by the Centers for Disease Control, was “attributable primarily to an increase in carbohydrate intake.” Though the
The identical conclusion could be drawn from the evidence gathered by the U.S. Department of Agriculture and published in a report entitled
In 1997, the University of Alabama nutritionist Roland Weinsier reviewed this evidence in an article entitled “Divergent Trends in Obesity and Fat Intake Patterns: The American Paradox.” “It appears that efforts to promote the use of low-calorie and low-fat food products have been highly successful,” Weinsier noted, but the reduction in fat intake did “not appear to have prevented the progression of obesity in the population.”
Population-wide assessments of physical activity are also difficult to make in any meaningful way. Those research agencies that traditionally study such things—the CDC’s Behavioral Risk Factor Surveillance System, in particular—have no evidence that would shed light on physical activity during the decade in which the obesity epidemic began. They do have evidence suggesting that Americans were no less active at the end of the 1990s than they were at the beginning of that decade, despite the continued rise in weight and obesity throughout this period. We know, too, that the obesity epidemic coincided with what might be called an exercise or sports epidemic in America, accompanied by the explosion of an entire industry dedicated to leisure-time pursuits. It’s worth remembering that in the 1960s Jack La Lanne was the nation’s only physical-fitness guru, Gatorade existed solely for the use of University of Florida football players, and skateboarding, in-line skating, snowboarding, mountain
