Saturday, June 9, 2012

Why We Get Fat

Why We Get Fat: and What To Do About It
© 2011, 2012 Gary Taubes
267 pages

The secret of weight, we are told, is as simple as physics, as the laws of thermodynamics. If we take in more energy in eating than we expend in exercise, we gain weight. If we use more energy than we eat, we lose weight. Hence the constant advice to those concerned about their bellies is to eat less and exercise more. Simple, right? ...then why doesn't it work?  Why do millions of people go on diets every January and struggle so mightily to do make any progress? And how can there be so many societies in history and at present where obesity is linked not to abundance, but to poverty? How can obesity and malnutrition exist in the same family at the same time?  Gary Taubes has an answer, one which explains in full the link between obesity, diabetes, high blood pressure, and cardiac problems while turning everything you think you know about diet on its head.

            Insulin is the key. Taubes writes like a volleyball player, delivering his argument with a bump, a set, and finally the spike. He begins by dismantling conventional explanations about weight control, pointing out that even studies done by institutions which dearly wanted to demonstrate an incontrovertible link between exercise and diet and weight loss have failed to do so. He then prepares the reader by pointing out that we already know that fat is managed substantially by hormones, pointing out the role estrogen plays in shifting body fat around at the onset of puberty. He also points out the way we observe fat utilized in other animals: is a Jersey cow lean because it eats lighter and runs laps around its field? Hardly. Jersey cows are bred as milk cows because their hormones prioritize turning food into milk, and Angus cows are bred as beef because their hormones emphasis turning food into fat and muscle. Calories and exercise have nothing to do with it – not in cows, not in rats, and not in humans.

            In humans, insulin is the chief hormone that manages fat. We’ve known this for decades, but somehow in the WW2 period the United States lost sight of the consequences. Essentially, when insulin is present in the bloodstream, we accumulate fat, and can’t get rid of it. When insulin is absent, our bodies are free to convert fat into fuel. To avoid gaining weight, then, we must avoid foods which stimulate the secretion of insulin, particularly carbohydrates and sugar. No carbs means no grain, no corn, and no rice. The idea of going “carbless” may strike modern readers as positively abnormal, but in truth the diet we’re “used” to is the strange one from the perspective of natural history. Humans evolved eating meat, fruit, and the occasional greens –  our dependence on grains is relatively recent, historically speaking. That dependence is one promoted by the idea which currently holds sway over dietary belief in America, that carbs are good and fat is bad: in most supermarkets, low-fat brands are the only option available. Not only is our love affair with carbohydrates fattening us up, says Taubes, but we've declared anathema a vital part of our diet.  We’re supposed to be eating fat, he says. The more fat in our diet, the more efficiently our bodies run -- and there's nothing to the idea that fatty diets lead to exercise, studies indicate.Here he and Michael Pollan concur.

The effective way to losing weight, then, is to avoid carbohydrates and eat heartily the diet of our ancestors – meat and greens. Fruit is more problematic because modern stocks have been bred to be far more sugary than their antecedents. This approach has been advocated by others; the famous Atkins Diet is based on it, for instance, and it’s very similar to the “Paleo” diet which is now gaining in popularity.  Why is there a link between obesity and poverty? Because poor societies rely on cheap foodstuffs – carbohydrate-rich foodstuff like bread and rice. Why is the Fast Food nation an obese nation?  Because carbohydrates are the appetizer, main course, dessert, and drink under the golden arches.
Why We Get Fat is a book of tremendous importance. In the United States today, diets low in fat are emphasized even as sugary sodas are sold in the public schools. Little wonder that despite the prolonged ad campaigns of the past decades,  obesity and its related diseases continue to become worse. Not only are we missing the point, but our attempts to address the problem only exacerbate it. Consider diabetes, a disease defined by our bodies’ inability to manage its blood sugar. The dominant form (Type 2) of diabetes is caused by our bodies becoming resistant to insulin: that is, it is less effective at moving sugar out of the bloodstream and into cells. Thus, our bodies have to produce more of it to do the job, and naturally the body becomes even more resistant to insulin, rather like we build a tolerance for alcohol. When the body’s demand for insulin product exceeds its ability to do so, we recognize diabetes…but our solution is to inject more insulin into the bloodstream.  This is a ‘solution’ that guarantees the problem will never be addressed at its root.  The lesson of Why We Get Fat is that we become insulin-resistant because our diet demands we produce an abnormal amount of the hormone. Change the diet to minimize insulin demand, and our bodies won’t develop that resistance.If that weren't enough, Taubes also pins the blame for high blood pressure and heart disease on it, though the latter is only a correlation.

Taubes has written two books in this vein; Good Calories, Bad Calories and this, Why We Get Fat. As I understand it, Good Calories, Bad Calories is the more substantial of the two, while Why We Get Fat is intended for a larger audience (har har) and emphasizes more application of the research. While Taubes doesn't promote a specific diet, the appendix does list various others (like Atkins) and provides general guidelines to eating. I've been doing my homework on Taubes' work for the last few months, since I first heard him in an extended interview on EconTalk, and I believe Why We Get Fat may be one of the most significant books I have ever read. Definitely recommended. 


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