Seventeen emergency crew members were needed to carry a 40-stone woman from a nursing home in Selsdon on Monday.
London Ambulance were called to Croham Place in Wisborough Road, Selsdon, to reports of a woman suffering breathing difficulties.
When paramedics arrived at the scene, they were forced to call the fire brigade for assistance in moving the patient from the 22-bed home that provides care for people with physical disabilities, into a specially reinforced bariactric ambulance.
A fire engine and fire rescue unit from Croydon fire station were sent to the address, where the crew supplied a basket stretcher which was used to help lift the woman on to a reinforced ambulance stretcher and trolley.
The 47-year-old was taken to Croydon University Hospital where she remains in a serious but stable condition.
Her father, who did not want to be named, said this was not the first time the fire brigade had been called to help his daughter.
He said: "This is the second time it has happened. The fire brigade were also called to help her about two years ago.
"She was always overweight, but gradually over the years she has put on more and more.
"She suffers from diabetes which makes her ill and overweight. She can't walk, so she can't do any exercise."
One firefighter called to the incident said crews had seen a noticeable increase in the number of times they are called to help obese people.
He said: "We are finding we are getting more and more of this type of calls.
"It wasn't a tricky job, but it was delicate.
"We formed a plan and between the ambulance staff and ourselves we got her on the stretcher and on to the trolley, but we did think about taking out a window to get her out."
Although there is not a specialist team dedicated to helping obese patients in need of medical care, the London Fire Brigade confirmed its fire rescue units are often sent to assist ambulance crews as they have special equipment which can be used to rescue both people and animals.
London Ambulance have three bariatric vehicles which are used to ferry obese patients.
The vehicles are equipped with double-width trolley stretchers and can also have hoists and special lifting cushions.
Two years ago the world's fattest man, who lived in New Addington, died of a heart attack.
David Hone, who weighed in at 61st, was desperately trying to slim but collapsed at his home, after starving himself to shed some weight.
Firefighters who were called to assist ambulance staff, winched the 48-year-old from his home Milne Park East, and he was rushed to Princess Royal hospital in a super sized ambulance, where he told doctors he couldn't stop eating.
His last weeks were spent on a reinforced hospital bed, which fell apart under his weight, or being hoisted around by a crane when he wished to move.
Mr Hone became the world's heaviest man after fellow-Brit Paul Mason, from Ipswich, shed 20st following gastric bypass surgery carried out after doctors warned him his days were numbered.
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