Thursday, August 16, 2007

If you can't show that obesity is bad, invent a new measure of obesity!

Note the rubric I have put in the journal abstract. It is admitted that by the old BMI measure fatties are not worse off and the new measure can be shown to produce an effect only by contrasting the extreme quintiles. It's a crock! It may show some danger for the hugely obese but for the vast majority of people it shows no danger. And extreme quintiles are in any case inherently at risk of being confounded with other factors. The claim that just a slightly enlarged stomach is bad for you is in fact CONTRADICTED by the study!

For many people, middle-aged spread is as much a part of getting older as laughter lines, receding hairlines and worsening hangovers. But research suggests that even the smallest of pot bellies may be a serious health risk. After examining more than 2,700 men and women with an average age of 45, scientists at the University of Texas Southwestern Medical Centre in Dallas found that those with even a little fat around their waists were significantly more vulnerable to heart disease, even if their overall weight was normal.

Their findings, published in the Journal of the American College of Cardiology (JACC), may come as a shock to many who would not consider themselves fat. But they reinforce a growing belief among medical experts that waist-to-hip ratio (WHR) is a more accurate measure of healthy shape than the widely used body mass index (BMI). BMI, which is calculated by dividing weight in kilograms by height in metres squared, gives an overall indication of heaviness compared with height. But according to BMI measurements, well-toned specimens from Brad Pitt to the rugby star Jonah Lomu would be classed as overweight, and increasing numbers of experts are now questioning BMI's usefulness.

The new study by James de Lemos and his team adds credibility to the theory that WHR is a more accurate means of measuring heart-disease risk because it identifies potentially dangerous "central obesity" even in those who are not overweight. The researchers conducted a series of examinations on their participants, ranging from blood sampling to MRI scans. All underwent imaging tests to look for early signs of calcium build-up in the arteries of the heart, which is linked to an increased risk of developing cardiovascular disease later in life. These deposits are a reflection of atherosclerosis - commonly referred to as "hardening" of the arteries - and can be detected years before a patient suffers chest pain or has a heart attack.

Researchers examined the relationship between body shape and early signs of disease in the arteries. They found that the likelihood of there being calcium deposits in the arteries grew in direct proportion to the increase in waist-to-hip ratio.

A breakdown of the participants into five groups showed that those with the highest WHR were almost twice as likely to have calcium deposits in their coronary arteries as those with the smallest WHR. Even when factors such as blood pressure, diabetes, age, high cholesterol levels and smoking were taken into account, the link remained strong.

Dr de Lemos said: "In our thirties and forties, we often gain three to four inches in the midsection. It's a day-to-day, meal-to-meal battle, but it's worth fighting. We don't have to clean our plates. It's better to throw food out than add it to our waists. Even a small pot belly puts us at higher risk when compared to a flat tummy."

June Davison, cardiac nurse at the British Heart Foundation, said: "People who are overweight or obese have an increased risk of developing heart disease. The risks are even higher when fat is mainly concentrated around the abdomen. "What's important is that people consider their body shape as well as their weight."


Journal abstract follows:

The Association of Differing Measures of Overweight and Obesity With Prevalent Atherosclerosis

By Raphael See et al.

Objectives: This study sought to evaluate the associations between different measures of obesity and prevalent atherosclerosis in a large population-based cohort.

Background: Although obesity is associated with cardiovascular mortality, it is unclear whether this relationship is mediated by increased atherosclerotic burden.

Methods: Using data from the Dallas Heart Study, we assessed the association between gender-specific obesity measures (i.e., body mass index [BMI]; waist circumference [WC]; waist-to-hip ratio [WHR]) and prevalent atherosclerosis defined as coronary artery calcium (CAC) score >10 Agatston units measured by electron-beam computed tomography and detectable aortic plaque measured by magnetic resonance imaging.

Results: In univariable analyses (n = 2,744), CAC prevalence was significantly greater only in the fifth versus first quintile of BMI, whereas it increased stepwise across quintiles of WC and WHR (p trend <0.001 for each). After multivariable adjustment for standard risk factors, prevalent CAC was more frequent in the fifth versus first quintile of WHR (odds ratio 1.91, 95% confidence interval 1.30 to 2.80), whereas no independent positive association was observed for BMI or WC. Similar results were observed for aortic plaque in both univariable and multivariable-adjusted analyses. The c-statistic for discrimination of prevalent CAC was greater for WHR compared with BMI and WC in women and men (p < 0.001 vs. BMI; p < 0.01 vs. WC).

Conclusions: We discovered that WHR was independently associated with prevalent atherosclerosis and provided better discrimination than either BMI or WC. The associations between obesity measurements and atherosclerosis mirror those observed between obesity and cardiovascular mortality, suggesting that obesity contributes to cardiovascular mortality via increased atherosclerotic burden.

J Am Coll Cardiol, 2007; 50:752-759

Can Organic Really Feed the World? Activism Disguised As Science

A new study published in an alternative agriculture journal has gained widespread attention by claiming that organic farming not only could adequately feed the world, it might even yield more food and require less farmland. It is a truly sensational claim.

In science, the more sensational the claim, the more robust the evidence needed to support it. This time, the evidence doesn't stack up. In fact, the evidence fell so far short that the journal that published the paper also published not one, but two scathing and dismissive "editorial responses" in the same issue. This is anything but a ringing endorsement.

A simple comparison of the authors of the paper and critiques is revealing. The "organic can too feed the world" authors are a collection of urban academics without any agricultural experience. The lead author studies fossil squirrel's teeth at the University of Michigan's Museum of Paleontology. The others are with Michigan's School of Natural Resources and Environment. In contrast, the authors of the two critiques are an agronomist at the University of Nebraska, Kenneth Cassman, and Colorado organic farmer Jim Hendrix.

As Cassman put it, "their analyses do not meet the minimum scientific requirements for comparing food production capacity in different crop production systems."

First, many of the studies they relied upon to support their claim simply aren't reliable. One large data set (comprising over half of the "yield ratios" they used to estimate food production in the developing world) are merely guestimates of increased productivity from a questionnaire sent to activists running organic "demonstration" farms. That doesn't even remotely approach "science," especially when the returned questionnaires include implausible organic yield increase claims of more than 500 percent. Another large dataset used by the Michigan researchers is so questionable that a paper critical of it published in the journal Field Crop Research was titled "Fantastic yields in the system of rice intensification: fact or fallacy?"

Central to this entire debate is the shortage of organic nitrogen fertilizer, a.k.a. manure. Currently, there is only enough animal manure to support one fifth of current global crop production. They only way to get more organically is to devote more land to legume crops or animal pastures that fix more nitrogen-which would require billions of acres of additional farmland the world doesn't currently have.

The Michigan researchers dismiss this sobering reality by calculating that, theoretically, enough nitrogen can be fixed by growing cover crops during fall/winter and between crops to make up the shortfall. As Dwight Eisenhower once stated, "Farming looks mighty easy when your plow is a pencil and you're a thousand miles from a corn field."

The final, sadly amusing testimony to the fantasy world occupied by these researchers comes from the conclusion of their policy forum article, where they point to the shining example of Cuba as "one of the most progressive food systems in the world" where organic farming is successfully feeding a country. Ah, yes, the famed Cuban "agricultural enlightenment" brought about by the ending of Soviet industrial fertilizer and pesticide donations.

How has Cuba fared after "going organic?" According to unofficial statistics, Cuba suffers massive food shortages and rations basic food staples. But don't take my word for it. Listen to these Cuban immigrants interviewed in a December 27, 2006 story on National Public Radio's Morning Edition:

Joel Lopez, a skinny 19-year-old who arrived on Dec. 14, 2006 in Miami through the [immigration lottery], or Bomba as it is called in Cuba. Through a translator: "Everything is so surprising here, the cleanliness of the streets, the food, the shops. Well, there is no comparison. . . . I have been telling [my friends] about a Chinese buffet I went to. I told them about how you can serve yourself again and again!"

Sitting next to him is Louisa Martinez. Her husband was a baker in Cuba. But still for her, it's the food that is the most dazzling. Through a translator: "Oh the food! Here there is a surfeit of food. Over there, there is a LOT of hunger. It's terrible."

So who are you going to believe: The urban pencil pushing elites, or the real farmers and real victims of the so-called "progressive food" movement?

Source. The three papers concerned can be found here


Just some problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

Trans fats:

For one summary of the weak science behind the "trans-fat" hysteria, see here. Trans fats have only a temporary effect on blood chemistry and the evidence of lasting harm from them is dubious. By taking extreme groups in trans fats intake, some weak association with coronary heart disease has at times been shown in some sub-populations but extreme group studies are inherently at risk of confounding with other factors and are intrinsically of little interest to the average person.


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