Council administrator Sarah Clegg lost nine stone after having an NHS operation at a private hospital to reduce her 28-stone weight, but became distressed when she started to regain weight.
There was no follow-up after the surgery by doctors and she developed a deficiency in zinc and selenium, which led to medical complications and her death.
An expert on gastric bypass follow-ups told a Sheffield inquest that zinc deficiency was likely to have been an important factor.
Sheffield Coroner Chris Dorries has asked Leeds Teaching Hospitals NHS Trust to check on all gastric bypass patients to ensure no others suffer a similar fate.
He said: “For all we know there may still be some poor soul out there. There needs to be a clear understanding in Leeds that they haven’t missed anyone.”
He said differing views on the importance of nutrient deficiency in gastric bypass patients needed to be canvassed and asked health officials to report back to him.
Mr Dorries said: “Somebody needs to sort that out on a national basis and I will be drawing it to the attention of the Chief Medical Officer.”
The Sheffield inquest was told that Miss Clegg, 35, had a gastric bypass on the NHS at the Nuffield Hospital in Leeds in January 2004.
Experts say all such patients need a lifetime follow-up to ensure no serious vitamin or nutrient deficiencies arise.
Although Miss Clegg was prescribed dietary supplements after the operation, she stopped her prescriptions in March 2005.
A slight zinc deficiency was noted in September 2005 and a surgeon said he would keep her under review, but she failed to attend two further appointments because she was embarrassed at failing to maintain her weight loss.
Recording a narrative verdict, Mr Dorries said: “She was wholly lost to specialist follow-up for reasons which are unclear.
“There was no attempt at telephone contact by the team in Leeds, advice to the GP or even formal discharge, although it is known that patients may seek to default when embarrassed about failing to lose weight.”
The surgeon accepted Miss Clegg, who lived in Clayton West, near Huddersfield, should have been chased up.
Mr Dorries said: “From March 2006 Miss Clegg was without follow-up of any kind.”
She began vomiting, suffered skin problems, and by September 2008 she was avoiding food. Her GP found her “ill and anxious” and she was admitted to Barnsley District Hospital with advanced vitamin deficiency.
Despite her family claiming she was seriously ill, Miss Clegg was discharged, only to be readmitted three days later nearly comatose and with heart failure.
It was only the next month that a dermatologist identified zinc deficiency. She was also found to have accidentally broken a rib in hospital before developing widespread pneumonia and dying on November 21, 2008.
Another expert said Miss Clegg’s lack of zinc caused a skin inflammation which damaged her liver and kidneys.
Mr Dorries said: “The micro-nutrient deficiency left Miss Clegg vulnerable to infection and with a reduced immune response.
“In consequence she developed an overwhelming and unusually rapid septic shock from a lung infection, leading to her death.”
Changes have already been made to gastric bypass surgery procedures at the Leeds trust.
Miss Clegg’s family said in a statement released after the inquest: “We hope that lessons have been learned from this tragedy.”