SHE underwent major obesity surgery after doctors warned that her 23-stone weight could kill her.

But after failing to fully adhere to strict dietary and nutritional requirements, Sheila Dunn died in York Hospital only nine months after her gastric bypass operation.

An inquest heard that the 52-year-old, of Thorpe Willoughby, near Selby, was classified as "super obese", which was putting great stress on her joints. Her Body Mass Index was almost three times the level it should have been.

In December, 2004, Mrs Dunn, who was cared for by her husband, Steven, decided to go through with the bypass operation in an effort to get her weight to normal levels.

Doctors said they were initially concerned when she lost more than four stone after the surgery, because she was not getting the right balance of food and fluids into her system.

Mrs Dunn's condition later worsened and she had to be given one-on-one care to ensure she took in the right vitamins.

York Hospital surgeon Glenn Miller, who carried out the surgery, told the inquest that patients must adhere to stringent dietary requirements and ensure they regularly take a course of vitamin supplements.

He said it was likely that Mrs Dunn was not taking the vitamins as assiduously as she should have been.

"This is a fairly extreme case," Mr Miller said.

"I've carried out 158 of these operations in York and this is the only case that has turned out like this."

York coroner Donald Coverdale said Mrs Dunn's death was not as a direct result of her operation and none of the medical staff at York Hospital were to blame.

He said he could not criticise Mrs Dunn as the operation required a huge change in diet and lifestyle.

"Dietary non-compliance has been a factor in her death," he said.

"The surgery itself was completely satisfactory."

Mrs Dunn died in August 2006 of a combination of cardiac arrest, obesity and malnutrition.

Mr Dunn told the inquest that he felt his wife could have received more psychological care. He said they could not force her to take the medication.

Mr Coverdale recorded a verdict of death by misadventure.

Mr Dunn declined to comment after the inquest.