obesity

The Economist on Obesity in America

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The CDC estimates obesity-related health care costs $147 billion per year. The Economist has a very skeptical take on whether America can do something about the obesity epidemic:

I very much doubt America is going to do anything, as a matter of public health policy, that has any appreciable effect on obesity rates in the next couple of decades. It’s not that it’s impossible for governments to hold down obesity; France, which had rapidly rising childhood obesity early this century, instituted an aggressive set of public-health interventions including school-based food and exercise shifts, nurse assessments of overweight kids, visits to families where overweight kids were identified, and so forth. Their childhood obesity rates stabilised at a fraction of America’s. The problem isn’t that it’s not possible; rather, it’s that America is incapable of doing it.

America’s national governing ideology is based almost entirely on the assertion of negative rights, with a few exceptions for positive rights and public goods such as universal elementary education, national defence and highways. But it’s become increasingly clear over the past decade that the country simply doesn’t have the political vocabulary that would allow it to institute effective national programmes to improve eating and exercise habits or culture. A country that can’t think of a vision of public life beyond freedom of individual choice, including the individual choice to watch TV and eat a Big Mac, is not going to be able to craft public policies that encourage people to exercise and eat right. We’re the fattest country on earth because that’s what our political philosophy leads to. We ought to incorporate that into the way we see ourselves; it’s certainly the way other countries see us.

I disagree. Here is one comment on what America can do:

1. Stop subsidising the production of grains (especially wheat and corn). This just makes cheap carbohydrates cheaper.

2. End USDA control of the “Dietary Guidelines for Americans”. The job of the USDA is to promote the sale of US agricultural products, not human health. There is an inherent conflict of interest here, which leads to guidelines that ignore the science.

3. Consider taxing (added) sugar, much like the other substances that create negative externalities are taxed (eg alcohol and tobacco).

The Mathematics of Obesity

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Carson Chow is an investigator at the National Institute of Diabetes and Digestive and Kidney Diseases, where he tries to figure out why 1 in 3 Americans are overweight. He’s an MIT-trained mathematician who is using his background to pinpoint why the obesity rate in America is so high (and will likely keep increasing). His interview in The New York Times is a good read:

Why would mathematics have the answer?

Because to do this experimentally would take years. You could find out much more quickly if you did the math.

Now, prior to my coming on staff, the institute had hired a mathematical physiologist, Kevin Hall. Kevin developed a model that could predict how your body composition changed in response to what you ate. He created a math model of a human being and then plugged in all the variables — height, weight, food intake, exercise. The model could predict what a person will weigh, given their body size and what they take in.

However, the model was complicated: hundreds of equations. Kevin and I began working together to boil it down to one simple equation. That’s what applied mathematicians do. We make things simple. Once we had it, the slimmed-down equation proved to be a useful platform for answering a host of questions.

What new information did your equation render?

That the conventional wisdom of 3,500 calories less is what it takes to lose a pound of weight is wrong. The body changes as you lose. Interestingly, we also found that the fatter you get, the easier it is to gain weight. An extra 10 calories a day puts more weight onto an obese person than on a thinner one.

Also, there’s a time constant that’s an important factor in weight loss. That’s because if you reduce your caloric intake, after a while, your body reaches equilibrium. It actually takes about three years for a dieter to reach their new “steady state.” Our model predicts that if you eat 100 calories fewer a day, in three years you will, on average, lose 10 pounds — if you don’t cheat.

Another finding: Huge variations in your daily food intake will not cause variations in weight, as long as your average food intake over a year is about the same. This is because a person’s body will respond slowly to the food intake.

More here.

Change Your Life in Twenty Minutes a Day

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Gretchen Reynolds, author of The First 20 Minutes: Surprising Science Reveals How We Can Exercise Better, Train Smarter, Live Longer, explains how you can change your life in just twenty minutes a day:

The first 20 minutes of moving around, if someone has been really sedentary, provide most of the health benefits. You get prolonged life, reduced disease risk — all of those things come in in the first 20 minutes of being active.

Two-thirds of Americans get no exercise at all. If one of those people gets up and moves around for 20 minutes, they are going to get a huge number of health benefits, and everything beyond that 20 minutes is, to some degree, gravy.

That doesn’t mean I’m suggesting people should not exercise more if they want to. You can always do more. But the science shows that if you just do anything, even stand in place 20 minutes, you will be healthier.

I haven’t read Gretchen’s book, but I am putting her philosophy to use in 2012. My advice: start at just five minutes a day and build up to twenty (or more). It might seem like an insurmountable obstacle in the beginning, which is understandable, but you’ll get there with practice…

The Fat Trap

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From the latest issue of New York Times Magazine, a discouraging statement for those of us trying to lose weight:

While researchers have known for decades that the body undergoes various metabolic and hormonal changes while it’s losing weight, the Australian team detected something new. A full year after significant weight loss, these men and women remained in what could be described as a biologically altered state. Their still-plump bodies were acting as if they were starving and were working overtime to regain the pounds they lost. For instance, a gastric hormone called ghrelin, often dubbed the “hunger hormone,” was about 20 percent higher than at the start of the study. Another hormone associated with suppressing hunger, peptide YY, was also abnormally low. Levels of leptin, a hormone that suppresses hunger and increases metabolism, also remained lower than expected. A cocktail of other hormones associated with hunger and metabolism all remained significantly changed compared to pre-dieting levels. It was almost as if weight loss had put their bodies into a unique metabolic state, a sort of post-dieting syndrome that set them apart from people who hadn’t tried to lose weight in the first place.

“What we see here is a coordinated defense mechanism with multiple components all directed toward making us put on weight,” Proietto says. “This, I think, explains the high failure rate in obesity treatment.”

While the findings from Proietto and colleagues, published this fall in The New England Journal of Medicine, are not conclusive — the study was small and the findings need to be replicated — the research has nonetheless caused a stir in the weight-loss community, adding to a growing body of evidence that challenges conventional thinking about obesity, weight loss and willpower. For years, the advice to the overweight and obese has been that we simply need to eat less and exercise more. While there is truth to this guidance, it fails to take into account that the human body continues to fight against weight loss long after dieting has stopped. This translates into a sobering reality: once we become fat, most of us, despite our best efforts, will probably stay fat.

As with many preliminary studies, the evidence is inconclusive. Yet, if it pans out, dieting and exercise books will have to be re-written.