The Obesity Era
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For the first time in human history, overweight people outnumber the underfed, and obesity is widespread in wealthy and poor nations alike. The diseases that obesity makes more likely diabetes, heart ailments, strokes, kidney failure are rising fast across the world, and the World Health Organisation predicts that they will be the leading causes of death in
all countries, even the poorest, within a couple of years. What's more, the long-term illnesses of the overweight are far more expensive to treat than the infections and accidents for which modern health systems were designed. Obesity threatens individuals with long twilight years of sickness, and health-care systems with bankruptcy.
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Of course, thats not the impression you will get from the admonishments of public-health agencies and wellness businesses. They are quick to assure us that science says obesity is caused by individual choices about food and exercise. As the Mayor of New York, Michael Bloomberg, recently put it, defending his proposed ban on large cups for sugary drinks: If you want to lose weight, dont eat. This is not medicine, its thermodynamics. If you take in more than you use, you store it. (Got that? Its not complicated
medicine, its simple
physics, the most sciencey science of all.)
Yet the scientists who study the biochemistry of fat and the epidemiologists who track weight trends are not nearly as unanimous as Bloomberg makes out. In fact, many researchers believe that personal gluttony and laziness
cannot be the entire explanation for humanitys global weight gain. Which means, of course, that they think at least some of the official focus on personal conduct is a waste of time and money. As Richard L Atkinson, Emeritus Professor of Medicine and Nutritional Sciences at the University of Wisconsin and editor of the
International Journal of Obesity, put it in 2005: The previous belief of many lay people and health professionals that obesity is simply the result of a lack of willpower and an inability to discipline eating habits is no longer defensible.
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Yet a number of researchers have come to believe, as Wells himself wrote earlier this year in the
European Journal of Clinical Nutrition, that
all calories are not equal. The problem with diets that are heavy in meat, fat or sugar is not solely that they pack a lot of calories into food; it is that they alter the biochemistry of fat storage and fat expenditure, tilting the bodys system in favour of fat storage. Wells notes, for example, that sugar, trans-fats and alcohol have all been linked to changes in insulin signalling, which affects how the body processes carbohydrates. This might sound like a merely technical distinction. In fact, its a paradigm shift: if the problem isnt the number of calories but rather biochemical influences on the bodys fat-making and fat-storage processes, then sheer quantity of food or drink are not the all-controlling determinants of weight gain.
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No one has claimed, or should claim, that any of these roads less taken is the one true cause of obesity, to drive out the false idol of individual choice. Neither should we imagine that the existence of alternative theories means that governments can stop trying to forestall a major public-health menace. These theories are important for a different reason. Their very existence the fact that they are plausible, with some supporting evidence and suggestions for further research
gives the lie to the notion that obesity is a closed question, on which science has pronounced its final word. It might be that every one of the roads less travelled contributes to global obesity; it might be that some do in some places and not in others.
The openness of the issue makes it clear that obesity isnt a simple school physics experiment. ...