Key Points:

Pacific Island nations have the most overweight people in the world, according to the most recent estimates by the World Health Organisation (WHO).

Eight out of the ten of the "fattest" countries are in the Pacific, the research found.

The top four - Nauru, Micronesia, the Cook Islands and Tonga - all have more than 90 per cent of their population defined as overweight.

A report published in Forbes magazine said increased Western imports and a significant change in diet due to closer economic ties with the US and New Zealand were partly to blame.

Other reasons given for the region's high obesity rates include a reliance on fatty, nutrient-poor imported foods and a decrease in the amount of physical labour.

"Obesity has become a problem of poverty," said Daniel Epstein of the WHO Regional Office of Americas. "Poor people have an easier time of eating junk food. People fill up on things that have a high caloric value but little nutritional value."

There is better news for New Zealand, which ranks number 17 in the world with an estimated 68 per cent of the population being classed as overweight - four places ahead of Australia.

WHO define anyone over the age of 15 with a body mass index (BMI) greater than or equal to 25 as overweight and a BMI equal or greater than 30 as obese.

How they rank:
TOP 10

1. Nauru, 94.5 per cent of population overweight
2. Federated States of Micronesia, 91.1 per cent
3. Cook Islands, 90.9 per cent
4. Tonga, 90.8 per cent
5. Niue, 81.7 per cent
6. Samoa, 80.4 per cent
7. Palau,78.4 per cent
8. Kuwait, 74.2 per cent
9. United States, 74.1 per cent
10. Kiribati, 73.6 per cent

SELECTED OTHERS

17. New Zealand, 68.4 per cent
21. Australia, 67.4 per cent
28. United Kingdom, 63.8 per cent
35. Canada, 61.1 per cent
43. Germany, 60.1 per cent
47. Vanuatu, 59.6 per cent
68. Fiji, 54.8 per cent
76. South Africa, 53.3 per cent
128. France, 40.1 per cent
148. China, 28.9 per cent
163. Japan, 22.6 per cent
193. Ethiopia, 5.6 per cent
194. Eritrea, 4.4 per cent

How to work out your BMI

1. Work out your height in metres and multiply the figure by itself.
2. Measure your weight in kilograms.
3. Divide the weight by the answer to question one (your height squared).

For example, if you're 1.6m (5ft 3in) tall and weigh 65kg (10st).
The calculation would then be:

1.6 x 1.6 = 2.56. BMI would be 65 divided by 2.56 = 25.39

The normal BMI range is 18.5 to 24.9. Adults with a BMI of 25 to 29.9 are considered overweight, and those with a BMI of 30 or greater are considered obese.

In New Zealand a BMI of 32 or more has been used to define obesity for Maori and Pacific people because studies have shown this slightly higher BMI is a more accurate index of fatness in these groups than that used for non-Maori and non Pacific people.