Fattier foods and a lack of exercise are blamed
The figures show that 55% of Tongan women, 74% of Samoan women and 77% of men and women living in Nauru are obese.
This is two times the proportion of overweight people in developed countries.
Unhealthy
The levels of obesity and chronic weight-related diseases in the Pacific have grown at an alarming rate, according to the report, which was prepared for the triennial Commonwealth health ministers meeting in New Zealand.
"This is placing a tremendous burden on the health and well-being of individuals and communities and upon health care workers," the report said.
Obesity is defined as an unhealthy amount of body fat. According to the World Health Organisation, an obese person is one whose body mass index, or weight in kilograms divided by the square of one's height in metres, exceeds 30.
The report blames the trend on a move away from traditional diets towards fattier, western-style foods and a lack of exercise.
Cultural notions
"The prevention and treatment of obesity in the Pacific is also made difficult by the traditional cultural notion that 'bigness' is a sign of wealth and power," the report said.
"In the Caribbean and many African countries, [obesity] is disregarded, ignored, neglected. It is just taken for granted that a poor, middle-aged woman gets fat and then dies from diabetes," he added.
Mr Rigby, who is attending the Commonwealth health ministers meeting, said obesity rates in New Zealand were also rising at an alarming rate.
New Zealanders fat
"New Zealand hasn't been spared the obesity epidemic," he said. "Never in the history of the human race have so many people been so fat."
In New Zealand, 15% of men and 19% of women are obese. But the condition is worse among the country's Maori women - 27% of whom are obese - and Pacific Island women, 47% of whom are affected by the condition.
He said juvenile obesity was also on the rise around the world because children were less active.
"The amount of hours spent watching TV has a direct effect on the obesity of children," Mr Rigby said.
Various strategies were proposed for dealing with obesity.
One was using taxes to encourage people to buy low-fat foods.
Others were making children walk or cycle to school and limiting the size of portions served at take-away restaurants.