D a recent flight to a scientific meeting, I was seated next to a pleasant 300-plus pound passenger. Both of us requested diet Cokes. Ironic, I thought. Considering the plethora of artificially sweetened beverages, diet, “light,” low-fat, no-fat, reduced calorie, and Olestra-laden products that are currently available—and yet, as a nation, we’re getting fatter and fatter. The latest figures show that more than half of all Americans are overweight or obese.1 Accordingly, there is a national obsession to be slim, with an astonishing 25 6 10% of Americans trying to lose weight at any given time of the year.2 Even the pharmaceutical industry has offered “solutions,” from amphetamines and thyroxine in the 1960s, to fenfluramine and phentermine (fen-phen), and now sibutramine in the 1990s. No nation in the history of the world has experienced the Y2K obesity problem that we have in the United States (US). In recent years, fashion designers have increasingly responded with elastic waistbands, “big and tall sizes,” and “loose-fit” styles. Moreover, the airlines have successfully marketed altered seat alignments and “more leg room” for their expanding passenger populations. In Baltimore, 19-inch seats in the old Memorial Stadium were replaced with 22-inch seats in their newly constructed ballpark, Camden Yards. Convenience or necessity? The proportion of US adults who are classified as obese (defined as a body mass index $30 kg/m) rose 49% between 1991 and 1998, with the greatest increases among the youngest age group, college-educated, and those of Hispanic ethnicity.3 During this time period, obesity increased in every state, in both sexes, and across all age groups, races, educational levels, and smoking statuses. The skyrocketing prevalence of obesity has created a major public health concern,4 because it is strongly associated with several chronic diseases, including type 2 diabetes, coronary heart disease, and metabolic syndrome X, or, as it is also known, cardiac dysmetabolic syndrome.5 This syndrome, which increases the risk of coronary atherosclerosis, is related to insulin resistance, in which obesity is a primary factor. A higher prevalence of hypertension, osteoarthritis, and gallbladder disease is also associated with increasing obesity.6 In 1998, in response to an emerging body of scientific evidence, the American Heart Association reclassified obesity as a major modifiable risk factor for coronary heart disease.7 Moreover, it is currently estimated that mortality due to overweight and obesity is second only to cigarette smoking in the number of deaths that could be prevented by behavioral change.8 However, researchers cannot agree on why there has been an outbreak of obesity. Is it genes, the campaign to reduce cigarette smoking, gluttony, or sloth? Unquestionably, genetic factors predispose a significant portion of the population to becoming overweight. Available data suggest that the genetic contribution to individual variations in body weight and fat stores lies somewhere between 25% and 70%.9–12 Nevertheless, there’s no evidence to suggest that the American genotype has changed over the past decade. Perhaps the campaign to reduce cigarette smoking, which has been effective, may be partly responsible? Smoking cessation is associated with a modest increase in caloric intake. Researchers have also shown that smoking 24 cigarettes over a 24-hour period increases the daily caloric expenditure by about 10%.13 Thus, caloric intake and energy expenditure can be expected to increase and decrease, respectively, when people stop smoking, thereby favoring a gain in body weight. Yet, the decrease in smoking itself is unlikely to explain the exponential rise in obesity, because the effect of smoking on weight is rather small and transient.14,15 Furthermore, it applies to ex-smokers only—a fraction of the population. Recently, a provocative report suggested that technologic advances provide the most likely explanation for the current rise in obesity.16 According to the theory, our current high-tech milieu has increasingly emphasized comfort and convenience with the development of time-saving and labor-saving devices, focusing on speed, rapid communication, improved efficiency, and increased productivity. In the current obesity-conducive environment, food has become readily accessible and, simultaneously, we have “engineered” physical activity out of our vocational and leisure-time pursuits. Our increased reliance on technology has resulted in constant pressure toward positive energy balance by promoting energy intake and discouraging physical activity (Figure 1).17 Food has become abundant and relatively inexpenFrom the Department of Medicine, Division of Cardiology (Cardiac Rehabilitation), William Beaumont Hospital, Royal Oak, Michigan. Manuscript received September 21, 2000; revised manuscript received and accepted November 27, 2000. Address for reprints: Barry A. Franklin, PhD, Cardiac Rehabilitation and Exercise Laboratories, Beaumont Rehabilitation and Health Center, 746 Purdy Street, Birmingham, Michigan 48009. E-mail: bfranklin@beaumont.edu.
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Apr 24, 2024
Ronaldo Lira‐Junior + 10
Open Access
