Interesting to me that most of the countries high up on the list are dominated by indigenous populations that are even less able to deal with modern carb-rich Western diets than European-based populations. E.g. I'm assuming New Zealand is so high because of Maori people.
Maori make up just 15% of the NZ population. They do however have more obese despite fewer who are only moderately overweight. Since the BMI ranking is by arithmetic mean, extremely fat people will have an outsize effect.
There's speculation (not sure if it's more substantiated than) that the obesity rates seen in the Pacific islands may also involve selection for humans who could amass energy stores necessary for long oceanic voyages.
