Florida State University : Research in Review

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Fat in Fashion?
Fat in Fashion?

Genes. Lack of exercise. A virus. The varied explanations for Americans' ballooning waistlines—and medical bills—have proliferated in recent years as the country has grown fatter, but none account for the whole picture.

So what's really going on here?

At the root of it all, say economists, is the cheap calorie. In June, Time magazine reported that “Americans still spend less to feed themselves than any other people on the planet…Just 9.9 cents of each dollar we spend is for food, down from 23.4 cents in 1929. By comparison, 16 percent of household expenditures in Britain go to food; Brazilians spend 23 percent, Thais 29 percent.”

But again, the price explanation doesn't fill in all the gaps. After food prices leveled off in the 1990s, Americans still packed on the pounds.

Now a new, unconventional economics model, drawing from not only economics but also sociological and biological research, is helping to complete the picture, at least for American women, who were the focus of the model published this summer in the journal Economic Inquiry.

Frank Heiland, FSU assistant professor of economics, and his colleague Mary Burke at the Federal Reserve Bank of Boston, theorize that cheap calories cause American women's initial weight gain, but beyond that, two additional factors kick in that largely explain the rest of a trend that saw nearly one-third of American women clinically obese by 2000.

Heiland and Burke suggest that by the end of the last century putting on a few extra pounds simply had become more socially acceptable. Data collected by the Centers for Disease Control and Prevention in Atlanta showed that in 1994, the average woman weighed 147 pounds and wanted to weigh 132 pounds. By 2002, the average woman weighed 153 pounds and wanted to weigh 135 pounds. The economists also cite as support another study from 2000 that found 87 percent of Americans, including 48 percent of obese Americans, said their body weight qualified as “socially acceptable.” Also shoring up the social component of Heiland and Burke's formula are recent findings, published this summer in the New England Journal of Medicine, that obesity spreads through social networks almost like a socially transmitted disease.

Still, food price and social contagion together don't explain the whole pattern of weight gain.

The third key factor the economists plugged into their model is metabolism. Though economists in the past decade have joined the many efforts to figure out the obesity epidemic, Heiland and Burke are the first to incorporate this biological variable, and as a result, Heiland says, their model so far best explains the pattern of weight-gain among American women.

Some medical researchers have shown that fat burns far fewer calories per pound than muscle, which is bad news for people already on the plump side. When Heiland and Burke incorporated this information into their model, their predictions matched more closely than any previous economic model the reality that not only has the average American woman's weight gone up in recent years but also that the heaviest women, the ones with the most pressing need to shed pounds, are the ones gaining the most.

The good news, Heiland said, is that women's weights have actually stabilized in the past few years as food prices have ticked slightly upward.

“I wouldn't be surprised if we've seen the worst of it,” he said. —C.S.