How the war on obesity went pear-shaped
With increasing evidence that a big belly probably won’t lead to an early death, it’s time to call a ceasefire.
Since the anti-obesity campaign is allegedly motivated by scientific findings, it would seem reasonable and prudent to make doubly sure that those claims are factual and trustworthy. Yet, we continue to find that the case against obesity is significantly flawed. Not only are the claims of an obesity epidemic often wildly exaggerated, but the science linking weight to unfavourable mortality outcomes is also frequently nonexistent or distorted.
For example, a study published in The Lancet medical journal last week has driven an empirical stake through the heart of the conventional wisdom that being ‘apple shaped’ increases one’s risk of a heart attack. The study found the risk of heart attack was not increased by fat being concentrated around the waist, which flatly contradicts earlier research that said overweight people with fat deposits in the middle of their body – or, to put it another way, having apple-shaped bodies - were three times as likely to suffer heart attacks than those with more generally distributed fat.
Who does and does not have an apple-shaped body is determined by measuring the waist-to-hip ratio – that is, comparing the distance around the hips and the distance around the waist to measure what is known as ‘central obesity’. Someone with a bulging middle is ‘apple-shaped’, someone with a narrower waist but fatter hips and bottom is described as ‘pear-shaped’.
The Lancet study was conducted by a research team led by Cambridge University’s John Danesh, which studied 220,000 people over the course of a decade. According to Professor Danesh, the study found that, ‘Whether assessed singly or in combination, body-mass index (BMI), waist circumference, and waist-to-hip ratio do not improve prediction of first-onset cardiovascular disease when additional information exists on blood pressure, history of diabetes, and cholesterol measures’.
As Danesh suggests, other researchers have suggested concentrating on a measurement of the waist alone, while many cling to BMI, which calculates obesity based upon a weight-to-height ratio. Because of its easy applicability, BMI is universally used in officially defining obesity, despite its manifest shortcomings. The BMI is wholly arbitrary and has no scientifically valid connection with mortality.
‘Obesity crusaders’ are what we call the individuals who manufactured the obesity-epidemic story in the first place and continue, through application of inherently flawed instruments, such as BMI and apple-body shapes, to misinform the public. They are a relatively small group of public-health officials in the US, the UK, the EU, and the World Health Organisation, assorted academics (very many with close ties to the weight-loss and pharmaceutical industry), the International Obesity Task Force, and a collection of so-called public-interest science groups.
How are these obesity crusaders reacting to the unambiguously good news published in The Lancet? Surely, they rejoice at the fact there is one less thing for a health-conscious population to fret over? No, they are not in celebratory mood. Quite the contrary. The obesity crusaders did not waste any time on the New Good News; after all, the Old-Time Religion continues to serve them so well.
Above all, the obesity crusaders stress that obesity is still bad for you. The British Heart Foundation’s associate medical director, Dr Mike Knapton, said it was clear that no matter how you measure it, obesity is bad for your heart. ‘[M]easuring our waist or checking our BMI are both quick and easy ways we can check our health at home’, he said.
Strangely, the obesity crusaders remain unaware that there is an absence of scientific evidence to support their assertions: firstly, that overweight and obesity increase one’s mortality risks; and secondly, that the overweight and moderately obese should lose weight because such loss will improve their health and lower their risk of heart disease.
In fact, the obesity crusaders’ assertions about weight and longevity ignore 40 years’ worth of international data that suggest obesity is not a cause of premature mortality. Many studies for different disease outcomes have demonstrated that the effect of both diet and physical activity are independent of the effect of BMI or various measures of body size or fat.
There is little credible scientific evidence that supports the claims that being overweight or obese leads to an early death. For example, Katherine Flegal of the Centers for Disease Control and Prevention found that in the US population there were more premature deaths among those who are normal weight than those who are overweight. Indeed, in this study, Americans who were overweight were those most likely to live the longest.
In the American Journal of Public Health, Jerome Gronniger found that men in the ‘normal’ weight category exhibited a mortality rate as high as that of men in the moderately obese category; men in the ‘overweight’ category clearly had the lowest mortality risk.
Moreover, a recent study published in the American Journal of Clinical Nutrition that looked at alternative measures of obesity, such as percentage of body fat, skin-fold thickness, waist circumference, and waist-hip ratio, found even less scientific support for the alleged fat-equals-early-death thesis. The authors report that for the intermediate level of each of the alternative measures of obesity, there was a negative link with mortality. In other words, those with a higher waist circumference or a higher percentage of body fat had lower mortality rates.
All of which should serve to remind us that the success of the obesity crusade rests not on the truth of its science, but on the way in which the obesity entrepreneurs use that science to change policy. Going forward, better policymaking will require, at a minimum, a far greater appreciation of the way in which science and its findings are both misrepresented and used by the obesity crusaders to distort the regulatory process.
Indeed, the last thing that the obesity crusaders would wish is to have rigorous science discount the circumstantial, indeed largely nonexistent, evidence on which the obesity epidemic is based. As the new study in The Lancet illustrates, the available knowledge is sufficient merely to label as reckless any crusade by self-appointed and self-serving public health authorities that profess to know what they plainly do not.
Patrick Basham directs the Democracy Institute and is a Cato Institute adjunct scholar. John Luik is a Democracy Institute senior fellow. They coauthored, with Gio Gori, Diet Nation: Exposing the Obesity Crusade. (Buy this book from Amazon(UK).)
KM Flegal and BI Graubard ‘Estimates of excess deaths associated with body mass index and other anthropometric variables’, American Journal of Clinical Nutrition 89 (2009): 1213-1219
KM Flegal et al ‘Excess deaths associated with underweight, overweight and obesity’, Journal of the American Medical Association 293 (2005): 1861-1867
JT Gronniger ‘A semi parametric analysis of the body mass index’s relationship to mortality’, American Journal of Public Health 96 (2005): 173-178
Doubts emerge over heart risk to ‘apple shape’, BBC News, 10 March 2011