"Urban transport systems based on a combination of rail lines, bus lines, bicycle pathways, and pedestrian walkways offer the best of all possible worlds in providing mobility, low-cost transportation, and a healthy urban environment." –Lester R. Brown, Plan B 4.0: Mobilizing to Save Civilization.
Obesity is reaching epidemic proportions, afflicting a growing number of people in industrial and developing countries alike. It is damaging human health, raising the incidence of heart disease, stroke, breast cancer, colon cancer, arthritis, and adult onset diabetes. In the United States, the Centers for Disease Control (CDC) estimates that 300,000 Americans now die each year from obesity-related illnesses.
Reducing obesity has traditionally focused on lowering caloric intake by dieting, but there is growing evidence that exercise deprivation is also a major contributor to obesity. With metabolic systems shaped by 4 million years of highly active hunting and gathering, many people may not be able to maintain a healthy body weight without regular exercise.
For the first time in history, a majority of adults in some societies are overweight. In the United States, 61 percent of all adults are overweight. In Russia, the figure is 54 percent; in the United Kingdom 51 percent; and in Germany 50 percent. For Europe as a whole, more than half of those between 35 and 65 years of age are overweight.
The number who are overweight is rising in developing countries as well. In Brazil, for example, 36 percent of the adult population is overweight. Fifteen percent of China's adult population is overweight.
Not only are more people overweight than ever before, but their ranks are expanding at a record rate. In the United States, obesity among adults increased by half between 1980 and 1994. Among Americans, 20 percent of men and 25 percent of women are more than 30 pounds (13.6 kilograms) overweight. Surveys in China showed that during the boom years between 1989 and 1992, the share of adults overweight jumped from 9 percent to 15 percent.
Juvenile obesity is rising rapidly. In the United States, where at least 1 out of 10 youngsters 6 to 17 years of age is overweight, the incidence of obesity among children has more than doubled over the last 30 years. Not only does juvenile obesity typically translate into adult obesity, but it also causes metabolic changes that make the disease difficult to treat in adulthood.
Obesity is concentrated in cities. As societies urbanize and people adopt sedentary lifestyles, obesity increases. In both China and Indonesia, the share of people who are obese in cities is double that in the countryside. In the Congo, obesity is six times higher in cities.
In a Worldwatch Paper, Underfed and Overfed, Gary Gardner and Brian Halweil report that the number who are overnourished and overweight has climbed to 1.1 billion worldwide, rivaling the number who are undernourished and underweight. Peter Kopelman of the Royal London School of Medicine summarizes the thinking of the medical community: “Obesity should no longer be regarded simply as a cosmetic problem affecting certain individuals, but [as] an epidemic that threatens global well being.”
Damage to health from obesity takes many forms. In addition to the illnesses noted earlier, heavier body weight increases resistance to the heart's pumping of blood, elevating blood pressure. It also raises the stress on joints, often causing lower back pain. Those who are obese are four times as likely to have diabetes as those who are not.
As weight goes up, life expectancy goes down. In analyzing this relationship for Americans between the ages of 30 and 42, one broad-based study found that the risk of death within 26 years increased by 1 percent with each additional pound (0.45 kg) of weight.
The estimated 300,000 Americans who die prematurely each year as a result of being overweight is nearing the 400,000 who die prematurely from cigarette smoking. But there is one difference. The number of cigarettes smoked per person in the United States is on the decline, falling some 42 percent between 1980 and 1999; whereas obesity is on the rise. If recent trends continue, it is only a matter of time before deaths from obesity-related illnesses overtake those related to smoking.
Gaining weight is a result of consuming more calories than are burned. With modernization, caloric intake has climbed. Over the last two decades, caloric intake in the United States has risen nearly 10 percent for men and 7 percent for women. Modern diets are rich in fat and sugar. In addition to sugars that occur naturally in food, the average American diet now includes 20 teaspoons of added sugar a day, much of it in soft drinks and prepared foods. Unfortunately, diets in developing countries, especially in urban areas, are moving in this same direction.
While caloric intake has been rising, exercise has been declining. The latest U.S. survey shows that 57 percent of Americans exercise only occasionally or not at all, a number that corresponds closely with the share of the population that is overweight.
Economic modernization has systematically eliminated exercise from our lives. Workers commute by car from home to work in an office or factory, driving quite literally from door to door. Automobiles have eliminated daily walking and cycling. Elevators and escalators have replaced stairs. Leisure time is spent watching television. In the United Kingdom, the two lifestyle variables that correlate most closely with obesity are television viewing and automobile ownership.
Children who watch television five or more hours a day are five times as likely to be overweight as those who watch less than two hours a day. Time spent playing computer games and surfing the Internet in lieu of playing outside is also contributing to the surge in obesity.
A common impulse of those who are overweight is to go on a diet of some sort, attempting to reduce caloric intake to the level of caloric use. Unfortunately, this is physiologically difficult given the abnormally low calorie use associated with our sedentary lifestyles. Ninety-five percent of Americans who attempt to achieve a healthy body weight by dieting alone fail.
Another manifestation of diet failures is the extent to which people are turning to liposuction to remove body fat. Resorting to this risky surgical procedure, which quite literally vacuums fat from under the skin, is a desperate last measure for those whose diets have failed. In 1998, there were some 400,000 liposuction procedures in the United States.
For many of those who are overweight, achieving a healthy body weight depends on both reducing caloric intake and burning more calories through exercise. Metabolically, we are hunter-gatherers. Given our heritage, exercise may be a genetic imperative.
Restoring exercise in our daily lives will not be easy. Today's cities, designed for automobiles, are leading to a life-threatening level of exercise deprivation. Our health depends on creating neighborhoods that are conducive to walking, jogging, and bicycling.
The challenge is to redesign communities, making public transportation the centerpiece of urban transport, and augmenting it with sidewalks, jogging trails, and bikeways. This also means replacing parking lots with parks, playgrounds, and playing fields. Unless we can design a lifestyle that systematically restores exercise to our daily routines, the obesity epidemic — and the health deterioration associated with it — will continue to spread.
Copyright © 2001 Earth Policy Institute