A reader writes:
Hawaii is not really the outlier you seem to think it is. While Hawaii as a state may have the lowest obesity of any US state, that is misleading. Obesity among native Hawaiians remains among the highest rates in the US (itself among the most obese countries in the world, at any rate). Moreover, unlike the other South Paciifc Islands mentioned in the post, the Hawaiian islands have a very high percentage of US armed forces - most of them in the left tail of the obesity curve. Also in Hawaii: lots of rich people, with the time and money to focus on their bodies. These two demographic factors no doubt skew the state's overall obesity rate. Control for them, and Hawaii is not that much different, I'd wager, than Tuvalu, Palau, and the rest.
Some startling findings from a 1991 study:
The results of a recent study showed that obesity is more common among Native Hawaiians than in other groups in Hawaii; 18 percent of the people living in Hawaii were reported to be overweight (20 percent or more over their ideal body weight), while 42 percent of Native Hawaiians were overweight. The results of a study performed between 1982 and 1987 showed that Native Hawaiians have the highest mortality of any ethnic group living in the US. Native Hawaiians have death rates from heart disease, diabetes, and cancer that are 44 percent greater, 22 percent greater, and 39 percent greater, respectively, than the entire US population.