Part of the problem was that Pacific Islanders were increasingly eating more imported processed food that is low on nutrients but high in calories, while shunning their traditional diets.
Children being "glued" to electronic gadgets with less physical activity was another risk factor.
Asked if Pacific countries should consider introducing a fat tax on junk food, Dr Tukuitonga said the idea had some merit.
"There's good evidence, based on the experience with tobacco where you ... put a tax on an item, it raises the price and you generally have reduced consumption," he said.
French Polynesia, Nauru, Fiji and Samoa have already introduced taxes on soft drinks.
Some Pacific governments are considering restrictions on television junk-food advertising.
Obese countries
1. Cook Islands 46.6 per cent of population
2. Palau 43.1 per cent
3. Qatar 40 per cent
4. Nauru 39.7 per cent
5. Niue 37.7 per cent
6. Marshall Islands 36.9 per cent
7. Tonga 36.4 per cent
8. Samoa 36 per cent
9. Kuwait 35.5 per cent
10. Tuvalu 34.5 per cent
21. Australia 28.4 per cent
22. New Zealand 27.7 per cent
(Source: World Health Organisation)
- AAP