The World Health Organisation ranks eight Pacific island countries among the world's top 10 most obese nations.
Unless drastic measures are introduced the region is headed for disaster, says the Secretariat of the Pacific Community's director-general, Colin Tukuitonga.
"Small fragile health systems in the region just won't be able to cope," Dr Tukuitonga told AAP.
Increased rates of diabetes, heart disease and kidney problems would also be a drain on the development potential of the Pacific because those most affect people in their 30s, 40s and 50s, the most productive working years, he said.
Part of the problem is Pacific islanders are increasingly eating more imported processed food that is low on nutrients but high on calories, while shunning their traditional diets.
Children who are glued to electronic gadgets and don't do as much physical activity are 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 also considering restrictions on television junk food advertising.
OBESE COUNTRIES RANKED
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)