The obesity epidemic has forced Ambulance Victoria to buy new heavy-duty vehicles, as schools and airlines are ordering wider seats. Even funeral parlours are super-sizing crematoriums.

Victoria has spent $1.4 million on four new ambulances for patients who weigh more than 159kg.

Paramedics treated and transported 1450 extremely obese patients during a trial of the state's only existing "complex patient transport vehicle" last year -- rising from one-a-day to five-a-day in just 12 months.

Ambulance Victoria has ordered four more of the $350,000 custom-built Mercedes vehicles to enter the service from April. They will transport patients up to 350kg.

Ambulance Victoria group manager Frank Cummane said the heavy-duty ambulances were a must.

"For the patient's sake, for our staff's sake and for the hospitals' sake, we couldn't safely transport these patients three or four years ago," he said. "Obviously you have to keep the dignity of these patients. Many of them cannot lie down as their weight makes it hard to breath."

Each customised vehicle is fitted with a 500kg hydraulic lifter, a stretcher that can carry up to 450kg, airbags to lift patients off the floor, a wheelchair capable of carrying a 295kg person and a double-sized seat to transport patients who must remain upright.

But paramedics are not the only ones feeling the pressure of the obesity epidemic.

Five years ago The Alfred hospital treated only 15 patients a year with serious weight problems -- now it caters for 50 with reinforced beds and larger theatre beds, toilets and CT scanners, as well as a bariatric team to visit housebound patients.

Baker IDI Heart & Diabetes Institute obesity expert Prof John Dixon said the number of super-obese people with a body mass index of 50 or more had risen fivefold in 20 years.

"They are a substantial part of our community, they are not going away, they are very much discriminated against and stigmatised," Prof Dixon said. "The ambulance services and hospitals should be congratulated for providing what is a right for citizens to have."

But weight control expert Dr John Tickell said 80 per cent of obese people could control their weight but choose not to, and governments and society were caving in to their problems.

"We live in a sick society where governments are reactive rather than proactive," he said.

Schools are now ordering chairs one size larger to cope with larger students, according to Glenn Webster of Woods Education Furniture. Airlines are also feeling the pinch - Jetstar is fitting its planes with seats 2.5cm wider.