A surgeon in New Zealand has received a dressing down for swearing at a severely obese patient.

The female patient made the complaint after a very tense consultation with her surgeon last year.

The New Zealand Herald newspaper reports the doctor said "f..." at least three times after the 44-year-old obese woman told him she did not like the word "diet" and preferred the term "lifestyle".

The doctor told his patient she was "going on a f...ing diet".

The woman was on a waiting list for gastric bypass surgery.

After she complained about his swearing, she received a letter from the surgeon saying they no longer had a "therapeutic relationship" and her name had been removed from his waiting list.

The doctor has admitted using bad language.

New Zealand's Health and Disability Commissioner said the conduct was insulting and unprofessional and he has recommended the surgeon attend a communication skills course.