AT RISK: Albert Buitenhuis, 50, and wife Marthie, 47, may be deported from New Zealand because Albert is considered obese.

A medically obese South African man has been told he is too fat for New Zealand, despite losing 30 kilograms since he moved to Christchurch six years ago.

Albert Buitenhuis and his wife, Marthie, are now facing deportation after their work visas were declined because of his 130kg weight.

Immigration authorities cited the demands his obesity could place on New Zealand health services.

New Zealand is the world's third most obese developed nation, behind the United States and Mexico, according to an OECD report released in June.

Buitenhuis, at 1.78 metres tall and with a body mass index of over 40, is considered medically obese.

However, he weighed 160kg when he first arrived in the country and his wife says he has committed no crime except "being a foodie".

The couple moved to Christchurch from South Africa in 2007 and got work at a local restaurant - Albert as a chef and Marthie as a waitress.

Their annual work visas had been renewed ever since with "very little problem", Marthie Buitenhuis said.

"We applied for [them] year after year and there were no issues. They never mentioned Albert's weight or his health once and he was a lot heavier then."

Then, on May 1, the couple received the news that Immigration New Zealand (INZ) had declined their work visas because medical assessors deemed Albert no longer "had an acceptable standard of health".

The couple were forced to stop working immediately. They are staying with his sister in Auckland while they fight to stay in the country.

"The irony is that at the moment he weighs less than he [did] when we first arrived in New Zealand and also less than in his first medical, which was accepted by INZ," Marthie Buitenhuis said.

An INZ spokesman said Buitenhuis was rejected because his obesity put him at "significant risk" of complications including diabetes, hypertension, heart disease, obstructive sleep apnoea, some cancers, premature joint disease, impaired glucose tolerance and an enlarged fatty liver.

He also had a long standing issue with a knee joint, which could cost up to $20,000 to replace.

"It is important that all migrants have an acceptable standard of health to minimise costs and demands on New Zealand's health services," he said.

Buitenhuis was the principal applicant on the work visa and so his wife was also no longer eligible for a work visa as a secondary applicant.

The INZ spokesman said further investigations about applicants' health were triggered when they had a Body Mass Index (BMI) level of over 35. Buitenhuis has a BMI of over 40.

"Unless it is in the extreme, obesity will not in itself cause an applicant to fail health screening requirements, but INZ's medical assessors have to consider to what extent there might be indications of future high-cost and high-need demand for health services," the spokesman said.

The couple have made an appeal to Associate Minister of Immigration Nikki Kaye and INZ said no action would be taken until she made a decision.

Buitenhuis said her husband's weight had not stopped him from contributing to society by working over 40 hours a week.

His weight "ballooned" to 160kg after he stopped smoking, but he had worked hard to lose weight.

A letter from his doctor shown to The Press stated he had "brought his cholesterol and blood pressure levels under control" and could reach the "acceptable level" of 100kg within 26 weeks.

"He has a big build but he has changed his whole lifestyle and has lost 30kg so far," Marthie Buitenhuis said.

"We've committed no crime and did nothing wrong other than my husband being a foodie."

Their former boss, Cashmere Club manager Don Whyte, said the couple had been "great employees".

"They've been here for years setting up a life, making friends and working hard. He's been the same size for years so either he should have been told back then he couldn't stay or he should be allowed to stay now."