Conquer National Obesity: Deport the Fat

In the summer issue of the journal International Migration Review, Lingxin Hao and Julie J. Kim argue that America's national obesity epidemic would be far worse than it is, were it not for mass immigration.

The average immigrant is slimmer than the average native-born American and stays that way for some 10 years after coming to the United States, says Hao, a sociologist at Johns Hopkins University, and Kim, a Hopkins Ph.D. candidate. Part of the explanation is self-selection: Migrating from one country to another (even under good conditions) is a challenge for even the fittest, and those who take the risk are usually in good health. And if immigrants get sick, they show what sociologists call the "salmon-bias effect," i.e., they head for home. What's more, the exercise and nutrition patterns of immigrants stay in place for a few years after they emigrate, giving them an "immigrant advantage" before they embrace America's fast-food lifestyle.

The typical native-born American male, 5'8" tall, weighs 187 pounds. This makes him officially seriously overweight, according to the Centers for Disease Control and Prevention. A man of that height should weigh 170 pounds, at most. His immigrant counterpart weighs, on average, 175 pounds. An immigrant woman of average stature is also about 12 pounds lighter than a corresponding native-born woman.

Roughly 30 percent of Americans are obese, which is defined as weighing more than 205
pounds for men of typical height, and 180 for similar women. One's body mass index, the formal measurement of healthy weight, tends to increase until age 60, then level off.

America would be better off if newcomers were innoculated against the national penchant for gobbling fries and shakes in front of the television. A shrewd public-health policy, Hao and Kim conclude, would aim to delay the erosion of the immigrant advantage.