"The cultural conditions for obesity are often already there in these populations, but something is stopping them from causing obesity in younger individuals," said La Velle, who noted that a significant disease load might play some part in this "masking effect" in Australia.
Obesity is also on the upswing among non-western immigrants to industrialized countries, as well as certain western groups undergoing rapid socioeconomic changes.
Barry Bogin of the University of Michigan Dearborn presented the case of the Maya in Guatemala and Maya in the United States, and discussed the impact of immigration on Mayan children.
While Maya-American children are taller and have longer legs than their Guatemalan counterparts, "an alarming number of Maya-American children exhibit weight problems," said Bogin, who noted that 42 percent of Maya-American children would be classified as obese by the standards set by the Centers for Disease Control.
Bogin's recent survey of these children suggests that variables like time spent watching television and playing computer games, along with family size and the primary language spoken at home, are some of the factors that influence the children's risk of obesity.
Contact: Monica Amarelo
American Association for the Advancement of Science