Junkfood Science: Obesity Paradox #4

March 17, 2007

Obesity Paradox #4

Many seem to be doing their best to convince us that the human race is doomed by poorer health and that obesity is killing us. Savvy consumers aren’t buying it.

We can simply look around and see the truth: our contemporary lives have never been better, we’re blessed with more people having enough to eat and not suffering malnutrition, we’ve never had such a glorious variety of safe food to eat and water to drink, our air is cleaner to breathe, more of our children are getting immunized and living healthfully through childhood, fewer women are dying in childbirth, educational attainment has never been higher, and everyone is living longer lives than ever. To actually believe all of the doom and gloom, we not only have to suspend reality, but also ignore over 50 years of government health statistics that show heart disease and cancer deaths rates are down. We’re living long enough to develop things associated with even older ages, such as Altzheimer’s. Rather than constructively focus energies and resources on actual issues and disparities in our culture, they’re being directed towards our appearances.

We’re bigger, although the actual changes in our weights and heights over generations are not nearly as great as we’re supposed to believe. Still, the evidence has proven a quandary for those who want us to believe that being fat is deadly. So much so, a special term has emerged to describe it: the “obesity paradox.”

When investigative researchers were recently unable to attribute heart disease to obesity, understandably, the story wasn’t widely circulated and, with a note of (likely unintentional) humor, they said “more research is needed to discover the links between obesity and cardiovascular disease.” The story headline craftily, but inaccurately, said: “Obesity’s Connection to Cardiovascular Disease Remains Poorly Understood.”

In reporting on the latest study, the Telegraph didn’t tiptoe around the bush:

Heart disease risk is largely genetic

Heart disease risk is largely determined by parents rather than lifestyle, new evidence from a large study in the United States suggests....The researchers looked at 1,697 offspring aged 30 and older whose parents had participated in a heart disease investigation in the US called the Framingham Heart Study. A wide range of risk factors were assessed, including age, sex, education, cigarette smoking, blood pressure, cholesterol level and body mass index (BMI), which relates height and weight.

...there was no clear association between parental longevity and BMI.

The Framingham researchers found that people who had parents who lived long lives, also appeared well on their way to living to ripe old ages, and that the risk factors popularly associated with heart disease — blood pressure, diabetes and obesity — were significantly determined by genes. Those blessed with the genes for longevity developed these age-related conditions at an older age. The research concurred with decades of observational and careful clinical studies.

The Telegraph also noted that in 2005, an international team of scientists were honing in on the specific genes for health conditions, including risks for heart disease, cancer and “obesity:”

While 4,000 diseases, from immune deficiencies to haemophilia, are linked with mutations in single genes, most major ailments, from schizophrenia to cancer, are linked to changes in large numbers of genes. The team from the Medical Research Council's Clinical Research Centre, London, revealed 70 genes that are important in “metabolic syndrome"...

The study of the Framingham cohort was led by Dr. Dellara F. Terry, M.D., MPH, in Geriatric medicine at Boston Medical Center. The researchers recognized that the body of research has found longevity runs in families and they set out to find out how strong the genetic links were, if they depended on if one or both parents lived beyond 85 years of age, and the affects on traditional heart disease risk factors. They looked at the data on men and women in the Framingham Heart Study who had been examined every 4-8 years since 1971 and their adult children. They found that it didn’t matter if it was one’s mother or father who lived longer, as either was associated with a 63% reduction in health risk factors, compared to those without a long-lived parent. But the chances of fewer risk factors tripled if both parents were long-lived. Numbers popularly believed to be measures of bad behavior, such as cholesterol levels, blood pressure and BMI, were actually genetically determined.

They found no difference in the BMI among the parents who lived a long time and those who didn’t. Being “normal” weight, overweight or obese was simply not relevant among those who lived long lives.

But interestingly, when they did a secondary analysis of just nonsmokers, they found a statistically significant association between increasingly higher BMIs among the parents and longer life. “The apparent “protective” association of weight progression with parental survival is counterintuitive,” they noted, especially given that everything we hear is that BMI is linked to heart disease and cancers.

Nor surprisingly, this didn’t make the news, just as the multitude of other studies similarly finding fatness of little signficance to mortality, and that fatness appears to be especially protective as we get older. When the evidence has been leaked, attempts to explain it away take two popular tactics.

One is to claim that the lower weights represent those who are diseased and in poor health, skewing the results. The problem here is that the most careful, quality studies account for this by not including those with chronic diseases and preexisting health problems, or experiencing involuntary weight loss. For example, the research of Dr. Katherine Flegal, Ph.D., and colleagues at the CDC’s National Center for Health Statistics discussed here, considered all such possibilities. That’s why it’s important to not just tally the number of studies on one “side,” but to look at their quality.

But this concern is also greatly exaggerated because, for example, as Dr. Paul Ernsberger and Paul Haskew wrote in their comprehensive review on the “Health Implications of Obesity:”

Weight loss is a late symptom in cancer, first appearing after the tumor has become massive enough to produce metabolic effects or pain, or as a side effect of chemotherapy.

They described multiple major studies which have examined peoples’ weights 10 and 15 years prior to death and found that longstanding leanness, not fatness, was the greater risk and a predisposing factor for cancer, noting, “it appears that leanness predates the development of cancer.”

Another popular claim is that people are fatter today so that we haven’t yet seen the long-term effects of obesity. This is nonsensical, too, as there have been numerous large studies examining the long-term effects of BMI and longevity. And even at the most extremes, the risks associated with obesity are considerably less than popularly believed, as discussed here.

While the cohort in this latest study was mostly white and middle-class, studies on all sorts of different population groups haven’t differed appreciably. According to Dr. Flegal and colleagues, there is no evidence for concerns of an impending health crisis because of fears being raised by those claiming we don’t know the long-term effects of obesity. As they carefully explained in a 2005 issue of the American Journal of Public Health, the CDC’s Epidemiological Follow-up Study in which body weights of Americans were measured a decade apart, found that among adults with normal BMIs only 2% had been obese 10 years previously and conversely, only 4% of obese adults had had normal BMIs while younger. Few people actually lose weight and keep it off, so we’ve already seen the effects of long-term obesity and varying body weights, they said.

Neither of these arguments applies to this latest study, however, because it examined BMIs throughout these people’s lives since 1971, not just at the time of their deaths. Their finding bear repeating: they found no association between longevity and BMI. In fact, among nonsmokers, higher BMIs were associated with longer, healthier lives.

© 2007 Sandy Szwarc

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