Economists tackle US obesity

Americans are eating more, not exercising less

By James Arnold BBC News Online business reporter

Why Americans just keep on getting fatter is a question that has obsessed health professionals, sociologists and politicians for decades.

Now, it seems, economists may have the answer.

David Cutler, Edward Glaeser and Jesse Shapiro, from the Institute of Economic Research at Harvard University, have mined almost a century's-worth of nutritional data in a hunt for lessons.

According to their survey*, the real culprit is not sluggish lifestyles or even fatty food, but technology.

As technological advances have made food ever more varied and convenient, the authors argue, the feeble will-power of the American public has been unable to compete.

Big problem

Almost all the rich world is struggling with bulging waistbands, but America is something special.

Increased calorie consumption can, of course, be a function of increasing wealth, and the average American swelled during the 20th century as result.

But since about 1980, the country has been beyond the point where further increases in weight would do anything other than harm life expectancy.

Yet the overeating has continued: the average calorie intake rose by about 10% between the mid-1970s and the mid-1990s.

Now, according to some calculations, close to one-third of Americans are clinically obese - about 50% more than even the chubbiest equivalent country.

Old ideas

The Harvard survey torpedoes most of the established theories for why this should be so.

It finds no evidence for one popular argument - that American portions are getting bigger.

Increased convenience has provoked a shift to frequent 'grazing'

Instead, the authors say, Americans are not eating more, just more often.

And claims that lack of exercise is to blame are decisively brushed aside.

Americans actually run around more than they used to, enough to compensate for their more sedentary working lives.

Even growth in time spent slumped in front of the TV seems to be slowing.

Many hands make light work

Instead, the culprit seems to be the division of labour.

In the mid-1960s, the average American non-working woman spent at least two hours a day on the family meals - now, that figure has halved.

At the same time, manufacturers of food have invested heavily in making their products tastier, cheaper, more varied and more convenient for the consumer.

The survey seems to indicate that producers' innovations were the direct cause of obesity

The authors point to the potato, which previously required laborious cleaning, peeling, chopping and cooking to make a meal, but which is now consumed by most Americans in the form of processed French fries.

The increased efficiency of food production - supplies per person have surged by 20% in the past two decades in the US - has driven down prices.

And its increased convenience has provoked a shift to frequent "grazing" - small but cumulatively hefty snacks, as opposed to regular meals.

Too tempting

This conclusion may not seem earth-shattering, but it has serious implications for policy makers.

First, it could shift the burden of guilt towards producers of food.

In the US, a small but vocal lobby is accusing big food firms of deliberately tempting consumers to overeat, in much the same way cigarette firms preyed on lack of self-control.

If producers could argue that consumers were at fault for being slothful, then there should be no case.

But the Harvard survey seems to indicate that producers' innovations were the direct cause of obesity.

Dismal science

Second, it undermines one of the basic tenets of economics - that increases in convenience and efficiency represent an unequivocal benefit for society.

The fact that Americans spend some $50bn annually on diet remedies shows that they can hardly be happy with the status quo.

The authors point out that the misery of the ailing few could be outweighed by the incalculable time-savings enjoyed by the nation's cooks, but admit that the picture is cloudy.

As the obesity rate keeps on swelling, however, weighing the costs against the benefits will only get easier.

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* "Why Have Americans Become More Obese?" Cutler, Glaeser & Shapiro, Harvard, January 2003.