Tongan Prime Minister Akilisi Pohiva has challenged other Pacific Island leaders to participate in a year-long weight-loss challenge to set an example to their national communities.

Mr Pohiva told a local newspaper he would propose the competition when the leaders meet next month.

Ten of the islands sit at the top of the world obesity rate rankings.

On some, up to 90% of the population are overweight, according to the World Health Organisation (WHO).

The region's obesity epidemic has been blamed on traditional diets of fish and vegetables being shunned for processed food imports and fatty meat.

In the interview with the Samoan Observer, Mr Pohiva hit out at the regional failure to combat childhood obesity and diseases like heart disease and diabetes.

"[It] has everything to do with our eating habits and our lifestyle and it is complex issue when it comes to our Pacific people," he told the newspaper.

"And with Pacific Island Leaders, we meet and talk and talk about this issue, yet initiatives on this issue is not making an impact, it doesn't seem to work."

He said he will propose the diet competition idea to his fellow leaders the annual Pacific Island Forum event held later this month.

"It is not about who loses the most kilos but in order to shake off the weight, you must eat light and having that healthy mentality will go a long way.

"Once the leaders are adapting to that mindset they would be determined to get their people on the same aspect and go from there," Mr Pohiva told the newspaper.