Numbers Reveal Gravity of Obesity Problem

Now may be a good time to remind ourselves that many of us are beginning to physically resemble the new palindromic year, 2002: wide, round, and symmetric-looking. A little arithmetic helps in assessing how heavy we've become.

American children, in particular, are fat and rapidly getting fatter. Furthermore, their fatness will likely lead to innumerable health problems as they age. These are the conclusions of a large study published last month in the Journal of the American Medical Association by Richard Strauss, a pediatrician at the Robert Wood Johnson Medical School in New Brunswick, N.J.

Oddly, the report also found that over 20 percent of minority children and approximately 12 percent of white children were at or above the 95th percentile in body mass (the definition of the body mass index, or BMI, appears below) and hence considered obese.

Fat Children and Bulging Percentiles

Given the children's heft, it is particularly intriguing to imagine how 20 percent of them could be shoehorned into 5 percent of the distribution of body mass (or any other measure). That is, how is it that fully 20 percent of the minority children in the study weighed more than 95 percent of minority children? (Similarly, 12 percent of white children in the study weighed more than 95 percent of white children.) This seems to be a variant of the situation in Lake Wobegon where all the children are above average.

The mini-mystery about the maxi-children is resolved when one realizes that the percentile rankings were based on body mass charts compiled decades ago. Twenty percent of today's minority children are as heavy as the heaviest 5 percent of minority children were between 1960 and 1980 (12 percent for white children).

Movement to Stop the Weight Gain

Resolving this seeming paradox underscores how serious the problem of childhood obesity is. Among the causes for its dramatic increase are the prevalence of junk food, lack of exercise, and excessive television and video watching. (Poverty is also a factor. Happily, the Segway Human Transporter is prohibitively expensive, but the new X-box promises countless hours of immobility.)

Among the consequences of obesity are increased rates of heart and circulatory disease, obstructive breathing disorders, and diabetes-related kidney, nerve, and vision problems. Furthermore, because of their youth, fat children have 40 years or more to develop these health problems.

Of course, this latest report doesn't reveal much more than a glance at the children standing around the local school playground. Having taken such a glance, Surgeon General Dr. David Satcher has called on schools to help children lose weight by improving physical education programs, instituting health awareness modules, and providing healthy food choices. (If so many schools weren't having enough trouble insuring basic literacy and numeracy, I might be less wary of this idea.)

Fat Adults and Round Numbers

And it's not just kids, of course. A trip to Europe or Asia, say, or a visit to the American heartland (perhaps stomachland is the more accurate term) makes our increasing rotundity quite clear.

According to some measures, more than 60 percent of American adults could be classified as either overweight or obese. Satcher estimates that because of the increased rates of the aforementioned diseases and conditions associated with it, obesity kills 300,000 Americans each year and rivals smoking as the leading cause of preventable death.

Statistical Sticking Points

Before the round number of 300,000 gains currency by being incessantly repeated, some arithmetical caveats regarding it should be raised. It is no doubt dependent on a variety of debatable assumptions.

What proportion of deaths from stroke, for example, ought we to attribute to obesity? How about deaths from diabetes? And how old, on average, are the people who die from obesity-aggravated diseases? What if one is obese for 20 years, permanently loses a lot of weight, and then dies from a heart attack 15 years later? What percentage of that death ought we to chalk up to obesity?

Different answers to these questions lead to widely different estimates of the number of deaths from obesity.

Problems with the definition of obesity are also difficult.

Do we use weight alone, historical charts, the body mass index or BMI (defined below), direct measurements of fat? And where do we place the cutoff lines without being too arbitrary? What about the special problems of defining early childhood obesity? How do we take into account a person's sex? Body-frame? Are there strong medical or normative reasons for our decisions? Is there any element of demonization of the obese present? Of cultural bias?

Obesity is an increasingly serious problem that can hasten death and lessen quality of life. Our response to it should be to lose our stomachs, not our heads.

Professor of mathematics at Temple University and adjunct professor of journalism at Columbia University, John Allen Paulos is the author of several best-selling books, including Innumeracy and A Mathematician Reads the Newspaper. His Who’s Counting? column on appears every month.