BioEd Online

Statements that the average US citizens has gained an inch since the 1960s, released last week, have been criticized as misleading by a Munich-based historian of economics.

The US National Health and Nutrition Examination Survey¹, published by the National Center for Health Statistics (NCHS) on 27 October, presents trends in estimates of mean weight, height and body mass index of adults from 1960 to 2002.

The main finding of the study is not contested. The weight of the average American is increasing alarmingly: the average for both men and women has increased by 11 kilograms over the past 40 years.

But the NCHS also publicized a second conclusion: "Adult men and women are roughly an inch taller than they were in 1960."

That is strictly correct. But it is misleading, says John Komlos, an economic historian at the University of Munich in Germany. Americans did increase in height by just under an inch between 1960 and 1970, but they have stayed roughly the same height since then, he says.

"American people have stagnated in height in the past three decades," he says, whereas Europeans are still growing. "Today western and northern Europeans are towering over Americans by as much as 7 centimetres and still growing."

The opposite situation held in the nineteenth century, Komlos notes, when Americans had a height advantage over Europeans of 3-9 centimetres².

Tall stories

Komlos believes that the NCHS may be trying to paint a rosier picture of US population trends than is warranted, perhaps to offset the dismal news of increasing obesity.

Komlos has used historical documents including army recruitment records to track trends in body measurements in Europe and the United States over the past two centuries. He investigates how the trends relate to living conditions such as nutrition, pollution and access to healthcare, which give what he calls a "biological standard of living". Height generally increases in times of prosperity and decreases when conditions are harsher.

He believes the NCHS survey reveals that in the second half of the twentieth century, US financial prosperity has not translated into a higher biological standard of living. He says the reasons include greater social inequality, inferior health and prenatal care and a worsening attitude to preventative medicine in the United States, compared with Europe.

Denying spin

Cynthia Ogden, the lead author of the NCHS survey, agrees with Komlos that most of the height increase reported happened before 1970. But she has a different explanation for the lack of recent growth. "There has been a lot of immigration in the United States, especially in the past few decades, and that affects things," she says.

Jeff Lancashire, a spokesman for the NCHS, denies that there was any attempt to place a positive spin on the report's findings. "In terms of height, people are getting slightly taller," he says. "But the biggest change has been the change in weight. There is no effort to downplay the weight gain."

He is also unconvinced that the report reveals poor living conditions. "You aren't going to see a huge increase in any population's height over those kinds of timescales," he says. "This is the first I've heard of dramatically taller people overseas."