An epidemic of obesity poses a a threat to world health, according to US scientists. Even in the poorest countries, many people are growing taller and heavier, to become at risk from the diseases of affluence: diabetes, heart conditions and cancer.
More than 60% of US adults are overweight. Until recently experts had assumed that in the developing world, the problem was one of malnourishment. But even in the developing world, there were urban communities rapidly becoming overweight.
"We are looking at a situation in which increased obesity and declining world health are inevitable," Marquisa LaVelle, an anthropologist at the University of Rhode Island, told the annual conference of the American Association for the Advancement of Science, in Boston, Massachusetts.
"We know that people have got taller, we know that foot size has increased, and in America we have reorganised stadium seats to accommodate larger... well, seats. One of our colleagues has estimated that just the extra leather for the increased shoe sizes would account for a distance from here to the moon and back."
The global pandemic of fat could not be explained by any genetic changes: it had occurred too fast. At bottom, societies were eating foods with higher densities of calories and fat, and becoming more sedentary.
"I tell my students, you did not cut a cord of wood before you came to class this morning," she said. "As anthropologists we are interested in the extremes of human adaptability and I think we are looking at it."
The epidemic had less to do with income, more to do with environment. African children of middle class parents in rural South Africa at the end of the apartheid years were likely to be leaner and more active than the children of low income families in the cities.
Barry Bogin of the University of Dearborn, Michigan, compared Mayan children in Guatemala with Mayans in US cities.
The city children were taller and more long-legged than their rural cousins - but also much heavier. "Nearly half are overweight and 42% are obese," he said. "And this childhood overweight is likely to lead to long term health problems and significant costs when the kids are adults."
Stanley Ulijaszek of the University of Oxford reported that once active, hungry cultures in the Pacific and Papua New Guinea were also affected. Around 77% of Samoan adults were obese; in Nauru, 65% of the population were grossly overweight. Once again, the swelling population could not be blamed on genetic changes. People everywhere were affected by the "McDonaldisation" of diet. "Humans are a particularly fat species," he said.
