Hospitals are spending up large on beds strong enough to cope with the strain of grossly overweight patients.

Middlemore Hospital, in Auckland's Counties Manukau health board area, is the latest to replace standard models with sturdier versions for patients weighing up to 180kg.

There are 126,200 overweight and 121,800 obese adults in the area and the hospital has designed new bathrooms, toilets and hallways to accommodate the severely obese.

The upgrade included the installation of expensive ceiling pulleys because nurses could not support and reposition heavier patients.

Middlemore spokeswoman Lauren Young could not reveal the exact cost but Waikato health board paid $4000 a bed during a similar upgrade last year.

Based on that figure, Middlemore's new beds would have cost about $1.5 million. They are additional to the hospital's 13 "bariatric" beds, for patients who weigh up to 500kg.

Many other health boards are scrambling to meet the needs of heavier patients. Waikato last year invested $3.3m in new beds, including $356,000 on extra-wide models for patients weighing up to 400kg.

Spokeswoman Mary Ann Gill said the beds they replaced were up to 50 years old and new models were needed regardless.

Wairarapa is replacing beds with models that hold up to 300kg. Capital and Coast's beds can hold 200kg but the board wants to upgrade to models that can carry 30kg more.

The Hutt board and the Waitemata board, which covers North and West Auckland, have beds for 180kg patients and no plans for upgrades.

Latest obesity figures indicate about 26 per cent of Kiwis are obese - up from 10 per cent in 1977.

According to the World Health Organisation, New Zealand men have the third highest Body Mass Index (BMI) rate and women the second highest.

Counties Manukau clinical director of health intelligence Gary Jackson said some of the region's biggest patients qualified for state-funded stomach-stapling operations, which cost about $28,000 each.

To get on the waiting list they have to have a BMI - a measure of body fat based on height and weight - of over 40, or over 35 with certain health conditions.

Almost 80 per cent of the Pacific Island population in the area are considered obese.

Jackson acknowledged there was an element of personal responsibility but said overweight people were not to blame. "It's easy to blame fat people but they're set up for failure," he said.

"It's frustrating because it's clear how to prevent it but the whole system is set up to help people get fatter."

Jackson pointed to the demise of the healthy schools scheme, the lack of space to exercise and poor socio-economic conditions.

He said the cost of new equipment was minimal compared with the cost of treating an overweight patient. "It costs $4000 per year to treat someone with diabetes or cardiovascular disease." Jackson said other patients cost an average of $1000 a year.

* 121,800: Obese adults in Counties Manukau.

* 26 per cent of Kiwis are obese.

* 500kg is the maximum weight for "bariatric" beds.