[Editor's note: We admire Sandy Szwarc for pointing out some of the excesses in America's war on obesity, such as lawsuits now brewing against fast food chains. But our nutrition director, Dr. Ruth Kava, objects to Szwarc's promotion of an odd, revisionist theory about obesity: that we are neither consuming more nor exercising less but are getting fat precisely because dieting causes metabolic changes that induce obesity. TS]
Over the past couple of weeks, Sandy Szwarc has contributed a ten-part series of essays on various aspects of the obesity epidemic that has been all over the news lately. Szwarc has made a number of statements about obesity, the increasing prevalence of obesity in the United States, and the purported reasons behind these phenomena that do not seem to me to be rooted in mainstream scientific data. Interestingly, she ends up where many mainstream health professionals do, advocating that people reach and maintain a healthy weight by adhering to a health-promoting lifestyle not smoking, eating a balanced diet in moderate amounts, and maintaining a healthy level of physical activity. It would be difficult for anyone to argue convincingly with this advice.
Szwarc is in perfect agreement with most health professionals in saying that obesity is more a more complex matter than simple overeating and laziness she'll find few people to argue with her about that. However, she also states that Americans have been eating fewer calories and exercising more over the decades that obesity rates have been rising. How can this be reconciled with the laws of thermodynamics? It can't.
The Increasingly Big Picture
In fact, the data do indicate that Americans are consuming more, not fewer calories per day than they did in the 70s. National surveys indicate that in the late 70s, adult men consumed 2,080 calories per day; in the '94-'86 Continuing Survey of Food Intake by Individuals, that figure had increased to 2,347 calories per day. Similar figures for adult women were 1,515 and 1,658 calories, respectively. These data are clearly summarized in a monograph available on the Internet at: http://www.stanford.edu/group/SITE/Shapiro.pdf (see Table 1). A large proportion of the increase was due to an increased number of calories consumed in snacks.
While memberships in health clubs and the number of health clubs may have climbed over the past fifty years, membership doesn't have to mean that a person actually goes to the club and exercises regularly. According to the Surgeon General's report Physical Activity and Health (US HHS, CDC, National Center for Chronic Disease Prevention and Health Promotion, 1996, Atlanta, GA), 25% of American adults report no leisure time physical activity; only 15% report engaging in vigorous physical activity at least three times per week during leisure hours. Similarly, 25% of young Americans aged twelve to twenty report no vigorous physical activity. During the decades of the 90s, the portion of high school students who reported being active for at least twenty minutes in gym classes decreased from 81 to 70%. These are not statistics describing an increasingly active population.
Szwarc maintains that it is lack of activity rather than obesity that imperils health and that it is possible to be fit and fat. Certainly, a heavy person who exercises regularly will be fitter than an equivalently overweight person who is sedentary. But in our society, obesity is often a hallmark of a sedentary lifestyle. And it is well known that excess body fat, especially when centrally distributed, indeed increases the risk of chronic conditions like hypertension and diabetes.
Fatten Them While They're Young
Unfortunately, Szwarc does not realistically address one very important issue the rapidly increasing proportion of American youth who are sedentary and obese. This proportion has increased dramatically over the past twenty years, such that in 1999-2000, 15% of six-to-nineteen-year-olds were overweight. In 1971-74, in contrast, only 4% of six-to-eleven-year-olds and 6 % of twelve-to-nineteen-year-olds were overweight (see http://www.surgeongeneral.gov/topics/obesity/default.htm and http://www.cdc.gov/nchs/products/pubs/pubd/hestats/overwght99.htm#Table%201). This is a frightening increase when one considers that an obese child has a greatly increased risk of becoming an obese adult. And obesity is indeed linked to type 2 diabetes.
According to the American Diabetes Association, type 2 diabetes (which used to be seen primarily in those over forty years of age) is now appearing in children and adolescents; anywhere from 8-45% of newly diagnosed diabetic children have the type 2 variety, and up to 85% of such children are obese (see http://care.diabetesjournals.org/cgi/reprint/23/3/381.pdf). Such statistics do not bode well for future public health. Diabetes is a major cause of blindness, amputation, and end stage renal disease in the United States. Usually, it takes years of having the disease before such complications are evident. So, if people develop diabetes at age forty or fifty, such effects may not appear until they are sixty or seventy. But if diabetes develops during the teen years, can we then expect an epidemic of young adults who develop these problems while in their 30s and 40s? This is not a scenario we should look forward to.
Fending Off Bad Advice with Bad Science
Szwarc seems to be of the opinion that if we recognize that obesity is not healthy (whether one considers it a risk factor by itself or an index of inactivity) we will inevitably encourage restrictive dieting, but this is not necessarily true. While all fad diets work in the short term since whatever their gimmicks, they tend to reduce caloric intake none have clearly been proven effective and safe over the long term. In fact, most responsible health professionals these days advocate attention to both caloric intake and expenditure, recognizing that a healthy body weight is the result of a healthy lifestyle. I've not heard anyone advocate "thinness" as a health goal, nor promote some ideal body weight.
In sum, one can discourage restrictive dieting without ignoring data and insisting that there is no health threat from obesity (whether in and of itself or as a marker of sedentary living). Dieting is not, as Szwarc suggests, likely to change the expression of a person's genes enough to make them become obese as an ironic unintended consequence. The facts are persuasive enough, the problem real, and unrealistic, overly-imaginative explanations for it are not likely to help anyone.