A person’s weight is not the primary indicator of their risk of an early death. People of the same BMI had a much higher risk of death if they had a waistline that exceeded a gender-specific threshold.
By Dan Gwartney, MD
In developmental biology, there is an understanding that form and function have a relationship. In other words, the way something is shaped or built affects what it does and how well it does it. Conversely, the function of a body part also affects the way it develops. This concept is easily recognized in real-world examples. Consider the skeleton – fish have cartilaginous skeletons; birds’ bones are very thin and hollow; mammals have dense, heavy bones. Fish do not require rigid weight-bearing frames; birds need to minimize bodyweight to achieve flight; mammals must support their frame against gravity at all times.
Darwin recognized changes in shape as part of evolution. He noted that the finches of the Galapagos Islands had developed beaks of varying shapes, to access different food sources. He theorized that creatures developed changes to meet the demands of the environment and that changes providing survival advantages were propagated through reproduction, leading to the “survival of the fittest.”1 Modern society is very unnatural in that disadvantageous phenotypes (basically a term describing an individual) are surviving and reproducing due to the support of the collective masses. In part, this is reflective of the moral development of humanity as the aged, infirmed and handicapped are provided for rather than being expelled from the “tribe” or killed outright. Animals typically force the weakest from the pack or prevent the runt of the litter from nursing; predators cull the weakest from a herd; in times of social crisis, even humans will often abandon the needy to serve their own interests.2
Yet, as it stands now, there is little environmental pressure to be fit. People receive greater reward for being personable or intelligent, rather than physical. Even among those who are unable or unwilling to provide for themselves, housing and food are made available. No demands are made upon Americans to labor except for those placed by the individual. This has contributed to a nationwide epidemic of obesity, with two-thirds of this nation’s citizens being above the normal weight range.3
When the concept of political correctness was introduced to society, the biases of prior generations began to erode under the steady influence of the media and government. While some of these changes were vital and well past due (sexism, racism, etc.) and promoted positive changes, other changes which may be just as legitimate might have caused the unintended consequence of removing social disincentives against unhealthy behavior. The clearest example of this is the social acceptance of obesity relative to its earlier status.
Anti-fat bias is the term used to describe a person’s conscious or sub-conscious attitude toward people based upon their weight or shape. Several studies found that not only did the public and media have an anti-fat bias, but so did many physicians.4 Efforts were made to increase the social acceptability of obesity and punish discrimination against oversized individuals. Tracking surveys established the condition of being overweight (as defined by body mass index) as the national norm; the global impression of the United States being a land of health and opportunity has changed to being a land of excess and obesity.
The methods available for affecting the behavior of large groups (e.g., a nation of 300 million people) are limited. In general, people respond to incentives and disincentives; incentives are rewards, whereas disincentives are punishment. It is impractical to offer every person in the United States a monetary reward or even a gold star for keeping his or her weight in the normal range. It is more practical to establish a system of disincentives; these may be social, legal or financial.
As was mentioned earlier, social disincentives relating to obesity have been removed, possibly affecting the rate of increase in average BMI. No longer are people universally stigmatized for belly rolls and double chins. Likewise, laws actually support the spread of obesity by blocking discriminatory hiring practices. There may be some financial disincentives (e.g., higher insurance premiums, airline seat charge, clothing alteration) but these are not prohibitory.
Whereas traditional disincentives have been ineffective or blocked, perhaps the most elementary disincentive may be effective: the threat to one’s health or life. People know not to touch a hot plate or run with scissors, those actions can cause harm.5 Being overweight has long been known to be associated with poor health.6,7 It is no surprise that people who are overweight suffer a higher risk of diabetes, cardiovascular disease, etc.8 Neither is it any surprise that someone who is obese has a higher risk of death than a normal-weight person.9,10
Weight is just a number though, and BMI (body mass index) is just a different number calculated from a person’s height and weight. A person is categorized as being overweight if his BMI is 25-30 and obese if the BMI exceeds 30. Yet, referring back to the visceral reaction a person has to another, greater bodyweight may actually be appealing. Arnold Schwarzenegger reigned as the world’s top bodybuilder from 1970-1975, weighing approximately 230 pounds at a height of 6’1”. Despite having the quintessential male physique, Arnold would have been considered obese. Why did people not react to his physique in the same way as others of the same BMI? As stated earlier, form follows function. People recognize an athletic or healthy physique and acknowledge that girth in the arms, chests and thighs is acceptable; girth in the gut is not.
This visceral response has been validated by science. In a study published in The New England Journal of Medicine that was immense in scope (359,387 people), reviewing the vital statistics of Europeans and their subsequent health, researchers confirmed the detrimental effect of obesity on mortality.11 However, in analyzing the data, a trend became clear, showing that a person’s weight is not the primary indicator of their risk of an early death. People of the same BMI had a much higher risk of death if they had a waistline that exceeded a gender-specific threshold. For men of normal BMI, those with a waistline that exceeded 40” were more than twice as likely to die during the study period (approximately 10 years) than men with a waistline of 34”; women were at a 78 percent greater risk if their waistline exceeded 35”, as opposed to being less than 28”. The risk is not restricted to those with the biggest bellies. As compared to the reference groups (less than 34” for men, less than 28” for women) each increase in waist circumference of two inches increased the risk of death by 17 percent and 13 percent respectively. Thus, a man with a 36” waist may be relatively healthy but he still has a 17 percent greater risk of death in the next 10 years than a man who can tighten his belt just two notches tighter.
The researchers did not ascribe any reason for this relationship, other than to acknowledge that visceral fat (the fat that surrounds the organs in the abdomen) releases hormone-like mediators that increase inflammation and induce insulin resistance. Visceral fat is a metabolically active tissue, unlike other deposits of fat in the body. Central obesity (a big waistline) is associated with a number of metabolic disorders, impaired hormone function and premature death.12-14
Form follows function; this is intuitively understood by most people. Attractive features are those that suggest good health; among these features is a slender waistline. Unfortunately, the harm caused by a big belly is not immediate and painful, like a hot stove. This allows people to ignore the risk sensed by all and proven by science. Sadly, the threat of death at some undefined point in the future is not a strong disincentive. Perhaps understanding that nature encodes people to find healthy features attractive will prompt everyone to grab that tape measure and pare down to a healthy size.
1. Marsh DE. The origins of diversity: Darwin’s conditions and epigenetic variations. Nutr Health, 2007;19(1-2):103-32.
2. Rohde D, Dewan S. More Deaths Confirmed in Homes for the Aged. The New York Times, 2005 September 15.
3. National Center for Health Statistics. Prevalence of Overweight and Obesity Among Adults: United States, 1999-2002. Available online at http://www.cdc.gov/nchs/products/pubs/pubd/hestats/obese/obse99.htm
4. Barclay L, Physicians not immune from anti-fat bias: a newsmaker interview with Marlene Schwartz, PhD. Medscape Medical News 2003 September 30. Available at http://www.medscape.com/viewarticle/462284
6. Adams KF, Schatzkin A, et al. Overweight, obesity, and mortality in a large prospective cohort of persons 50 to 71 years old. N Engl J Med, 2006 Aug 24;355(8):763-78.
7. Jee SH, Sull JW, et al. Body-mass index and mortality in Korean men and women. N Engl J
Med, 2006 Aug 24;355(8):779-87.
8. Ordovas JM, Corella D. Metabolic syndrome pathophysiology: the role of adipose tissue. Kidney Int Suppl, 2008 Dec;(111):S10-4.
9. Janssen I, Bacon E. Effect of current and midlife obesity status on mortality risk in the elderly. Obesity (Silver Spring), 2008 Nov;16(11):2504-9.
10. Yan LL, Daviglus ML, et al. Midlife body mass index and hospitalization and mortality in older age. JAMA, 2006 Jan 11;295(2):190-8.
11. Pischon T, Boeing H, et al. General and abdominal adiposity and risk of death in Europe. N Engl J Med, 2008 Nov 13;359(20):2105-20.
12. Ghandehari H, Le V, et al. Abdominal obesity and the spectrum of global cardiometabolic risks in US adults. Int J Obes (Lond), 2008 Dec 9. [Epub ahead of print]
13. Demerath EW, Reed D, et al. Visceral adiposity and its anatomical distribution as predictors of the metabolic syndrome and cardiometabolic risk factor levels. Am J Clin Nutr, 2008 Nov;88(5):1263-71.
14. Mason C, Craig CL, et al. Influence of Central and Extremity Circumferences on All-cause Mortality in Men and Women. Obesity (Silver Spring), 2008 Oct 16. [E-pub ahead of print]