Vanishing Automobile update #46

The Airlines Made Us Fat

February 10, 2004

A recent report from the Centers for Disease Control reveals that America's obesity epidemic (if there is one -- see update #25) isn't caused by the suburbs at all. Instead, it is the result of airline deregulation.

Actually, the report says we are fatter because we are eating more. Between 1971 and 2000, the average number of calories consumed by American men grew by 7 percent, while the average consumed by American women grew by 22 percent. We are consuming less fat as a percentage of our diets, but because we are eating more total, we are consuming more total fat. But the main thing that has increased is our carbo intake, suggesting that all the low-carbo foods suddenly popping up on supermarket shelves and in fast-food restaurants may not be such a bad idea.

Like the obesity data, the "energy intake" data come from four telephone surveys, conducted roughly a decade apart (roughly 1971, 1980, 1990, and 2000). Survey methods varied from survey to survey -- always a warning sign. For example, one of the surveys interviewed 3,700 people while another interviewed more than 14,000 people.

A close look at the data reveals that the 1971 and 1980 surveys found no significant changes in diet. The same is true for the 1990 and 2000 surveys. Between 1980 and 1990, however, men's caloric intake increased by 9 percent and women's by 18 percent. Most of the changes in fat vs. carbos also took place in that time period.

An editorial note accompanying the report says that "factors contributing to the increase in energy intake include consumption of food away from home; increased energy consumption from salty snacks, soft drinks, and pizza; and increased portion sizes."

Now, what took place between 1980 and 1990 that would lead people to consume more food away from home? Obviously, it was airline deregulation, which led to lower fares, which led to much more travel. On top of that, the airlines are always foisting salty snacks and soft drinks on their passengers. Clearly, the airlines are responsible for making us fat, and the solution to the obesity epidemic is to reregulate the airlines, allowing them to raise fares and discourage fat-inducing travel.

Of course, blaming obesity on the airlines makes no more sense than blaming it on the suburbs. As Wendell Cox found, an earlier report that blamed obesity on the suburbs found that people living in Chicago exercise 40 seconds a day more than people living in Chicago's suburbs. That hardly sounds like a reason to demonize the suburbs.

In fact, the data in the energy-intake report itself are questionable. The report warns that "information on dietary intake is self-reported and subject to recall bias." It adds that "changes in the interview method" between the 1980 and 1990 surveys "might account for some of the difference." The later survey asked people about their diets on weekdays and weekends, while the earlier report focused solely on weekdays. "Food consumption differs on weekend days," the report dryly observes.

Even without those sources of error, the report's data are inconclusive. The standard error for men is plus or minus 25 percent while the standard error for women is plus or minus 13 percent. That means that there is no statistically significant difference in the estimates of calorie consumption between any of the time periods.

So the mystery of the obesity epidemic remains: Are we getting fatter? What is the cause? What can or should government do about it? The only thing that is clear is that we don't have enough information today to justify any government policy that aims to reduce obesity.

Thoreau Institute | Vanishing Automobile | Vanishing Automobile Updates