Scientists revealed a "thrifty" gene variant on Monday that likely helped Samoans store fat and survive in bygone lean times, but has made them among the portliest people in times of plenty. The variant in the gene CREBRF was common among Samoans - it was present in 45 percent of some 5,000 participants in a study, a research team reported in the journal Nature Genetics.
"Those with it were likely to have a higher BMI than those who didn't have it," they wrote - referring to the international measure of "body mass index" - a ratio of weight-to-height squared.
Having the variant was associated with 35 percent higher odds of being obese, said a statement from Brown University in the United States, which was involved in the study.
The variant is virtually non-existent in Africans, Europeans or their descendents, and is "very, very rare" in East Asians.
According to the study authors, 80 percent of Samoan men and 91 percent of Samoan women were overweight or obese in 2010.
And while genetics cannot bear all the blame, it does complicate matters.
"We believe that this variant became so much more common in Samoans because it was historically advantageous to them as a population," study author Stephen McGarvey of the Brown University School of Public Health told AFP.