Junkfood Science: Where’s the crisis?

April 02, 2007

Where’s the crisis?

For more than a dozen years now, we’ve been given frightening images of a childhood obesity epidemic: an epidemic of immense, sickly children that’s reached pandemic proportions.

When asked, most people probably believe that today’s children have become at least twice as fat as in past generations and plagued by health problems. That’s certainly the alarming image of the childhood obesity epidemic portrayed in the media. But how many of us have stopped to examine the evidence and see for ourselves just how real and realistic the threat is to our children?

As we learned in the “Anatomy of an epidemic,” how an epidemic is defined and marketed, and the intensity of efforts to identify cases, can create an epidemic where the evidence shows only modest increases in actual numbers and actual weights.

In creating the perception of a crisis, media and public health officials have spoken with unified certainty of a fat time bomb and a tsunami that’s shortening the lives of our children.

In the past 25 years, the health status of our children has deteriorated and with it, their ability to learn and become productive members of society. The proportion of overweight children has tripled, and the number of children who suffer serious medical, psychological and social repercussions has increased. High blood pressure has quadrupled...Other chronic diseases...that used to be associated with older adults are now increasingly diagnosed in children. Hospitalization costs for children with obesity-related conditions tripled between 1977 and 1999. — Dr. Maria Goldstein, M.D., of the Childhood Obesity Task Force and steering committee creating New Mexico’s Strategic Action Plan, Physical Activity and Nutrition in the Schools, sponsored by Action for Healthy Kids and officially endorsed by the Governor’s Council on Physical Fitness and Health. (Albuquerque Tribune, February 1, 2005)

A tripling of childhood obesity sounds like a very real and dangerous threat, indeed. But, as we’ve learned, it is based on the prevalence, or numbers of children who fall within the definition of “overweight” and “obese” — not on actual weight increases among children. It can take the merest growth in height or weight to tip a child into the rosters of “too fat.”

For the first time in our history, we’ve had several generations of children who’ve largely been able to enjoy their childhoods free from starvation, food shortages and rationing; able to receive an education rather than toil alongside their parents; and saved from the ravages of high infant mortality and devastating childhood diseases that have been largely eradicated thanks to immunizations, improved health care and safe water. Instead of expending calories battling infections, more children than ever are surviving infancy and childhood and growing up healthier and larger. Population-wide, we have fewer scrawny malnourished children. Thanks to these positive advancements and better childhoods, every actual health statistic shows lifespans increasing and diseases dramatically dropping. And there is absolutely no evidence to support fears that children’s lives will suddenly shorten.

The popular assumption that the resulting increases in our children’s sizes are somehow pathological can be critically questioned per the scientific evidence. But we never hear the full story, with good reason. If the facts were more widely known of just how modest the actual increases in children’s sizes have been over the past forty years, it is doubtful that anyone would be as sold on the idea of a crisis.

So instead, we hear about skyrocketing increases in the prevalence of obesity — but even these figures have been carefully crafted to give us an exaggerated perception. There are all sorts of figures bantered about, too, which can make it hard for consumers and professionals to keep track. The most overstated numbers are based on self-reported surveys, including the Behavioral Risk Factor Surveillance System data. BRFSS is a telephone survey that’s been conducted by health departments since 1984. Helping to skew the results, only those with land lines are included, eliminating many of higher socioeconomic status; and as more publicity has been given to obesity over the years, people have been more likely to participate and to more accurately report their weights. In contrast, the National Health and Nutrition Examination Surveys (NHANES) have been conducted since 1963 and involve a representative sample of thousands of Americans with actual physical examinations, measurements and labwork taken by professionals.

In interpreting the data, the definitions for “at risk for overweight” and “overweight” for children and teens (and “obese” adults, for that matter) have been changed. For years, kids’ and teens’ definitions had been based on 85th and 95th percentiles on weight and height growth charts designed forty years ago. As today’s children are maturing earlier and are taller and larger than past children were when the growth charts were developed, more were falling in the top percentiles.

Then, as we reviewed in “New Age Numerology,” when the CDC redesigned the growth charts in May 2000 and made them BMI-based, nearly two-thirds of children suddenly found themselves in higher percentiles. According to the CDC, when the same definition for overweight was applied to all of the NHANES data, the numbers of “overweight” children and teens was actually fairly stable from 1960s to 1980. But that’s not all....

Take a look at the percentages of children who’ve fallen within the clinical definitions for “overweight” (“obese” by today’s popularized term) over the years:

In just the 8 years between 1980 and 1988, prevalence of “overweight” nearly doubled. And it increased another 50% in just 5 years between 1994 and 1999.

Doesn’t that strike you as odd? It’s interesting that no one has looked into just why the statistics show such dramatic surges in such short time periods, because, as we’ve seen, there have been no notable changes in the calories or diets of children, or in their activity levels, since the 1960s to explain it — just a lot of phoney claims to make us believe something sinister has been going on. It’s also just plain easier and profitable to jump on the “epidemic” bandwagon.

But it is disingenuous for health officials to not explain what changed. The NHANES surveys are statistics gathered on a population of people. But the surveys themselves are different. The more recent surveys have undergone significant design changes, in order to better reflect the increasing diversity and aging of our population. They have been done on different people and different demographic groups over the years. Earlier surveys didn’t reflect much racial diversity so when they were redesigned, selected population groups were suddenly disproportionately sampled in large numbers: children under 5 years, elderly over 60, and minorities. Black and Mexican-Americans, which according to the CDC are twice as likely to be "overweight" than whites, each now represent 30% of the total sample populations. So trying to compare surveys is like comparing apples and oranges. Never mind that population statistics cannot be used to make any credible conclusions about individuals.

Still, during the height of the government’s build-up of its anti-obesity initiatives during 1999-2004, the NHANES data was not supportive of an obesity epidemic. Yet an epidemic was needed to justify their programs and every vested interest continued to make increasingly frightening claims. Meanwhile, a critical study was virtually buried in the media. The CDC National Center for Health Statistics report published in the June 2004 issue of the Journal of the American Medical Association, found that there had been no change in the prevalence of overweight and obesity among U.S. children, teens or adults since 1999 to 2002!

It’s been equally difficult for consumers and healthcare professionals to learn how much average weights and heights (the two parts of the body mass index computation) among children and teens have actually increased. The available figures based on actual body measurements taken as part of NHANES suffer from the same difficulties in making conclusions because our population has become more diverse over the decades. Even so, the measurements since 1963 paint a considerably different picture of the “childhood obesity epidemic” than we’ve been led to believe.

The average weight of a 10-year old boy surveyed in 1963, for instance, was 74.2 pounds; and less than 85 pounds in 2002 — an increase of around 10 3/4 pounds over the past 40 years. Similarly, the average 10-year old girl today weighs about 10 1/2 pounds more than girls surveyed 40 years ago. The figures for teens over the past 36 years show nearly identical differences. Meanwhile, over the past 4 decades, the average 10-year old girl is about 1 inch taller, as is the average teenage boy.

These modest increases in population-wide heights and weights have been over nearly 40 years — a period when life expectancies have increased 10%, to the longest in our history, and age-adjusted rates for chronic diseases have dramatically dropped.

Information enables us to give a more critical eye to the inordinately extreme claims about the deadliness of “childhood obesity” and doom and gloom threats about our children’s health. We can most credibly ask “where’s the evidence for a crisis?”

© 2007 Sandy Szwarc. All rights reserved.

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