A man who shed 10 stone was refused bariatric surgery by NHS Fife because he still did not meet their weight loss criteria.
Martin Keatings, 32, was told he must lose 5% of his body mass but weight he had already lost did not count because it was before his referral.
He claims the chances of ridding him of his type II diabetes, the main purpose of the weight loss operation, have diminished in the two years since.
NHS Fife has been told by the Scottish Public Services Ombudsman to apologise to Martin, from Cairneyhill in Fife.
The ombudsman found it was unreasonable to bar Martin’s progression to the next stage of treatment solely because he did not meet the 5% criteria.
It also said the health board did not give reasonable consideration to his prior weight loss and his other health conditions and a chance for a second opinion or appeal should have been offered.
Martin, who suffers from ME, developed severe neuralgia in his legs, which in turn saw his weight balloon to 30 stone and resulted in diabetes and sleep apnoea.
He lost 10 stone on his own but said he was unable to lose any more due to medical issues.
Continuing pressure on his legs at 20 stone meant he remained in a lot of pain and he was referred by his GP to the Fife adult weight management service.
Martin said bariatric surgery was advised but he fell foul of NHS Fife’s adherence to national guidance and was refused progression to the surgery stage of the treatment programme.
He said: “They told me that I would have qualified if I had been referred to them then lost the 10 stone, so I was penalised for losing weight before the referral and not wasting NHS resources.”
He added: “I have been put at risk of progression of illness due to the weight itself, not to mention risk of progression of diabetes and also the possible future complications from long term pain medication use which could be reduced if the pain in my legs was reduced, which only comes from reducing the weight on my legs.
“The strange irony of this entire situation is that when I originally complained to the NHS I made a fiscal case to them.
“The costs associated with the surgery are 10 times less than the projected course of managing my illness over the next 10 years.”
NHS Fife was approached for comment on Tuesday afternoon and responded on Friday morning.
Helen Buchanan, director of nursing, said: “NHS Fife is unable to discuss individual patients or their care.
“We strive to provide the best quality care to all patients through the Fife adult weight management service, offering a comprehensive support programme, incorporating numerous elements including ongoing lifestyle, psychological and physical assessment in preparation for any surgery.
“In this instance it is clear that some elements of care fell short of our high standards and we are in the process of carefully reviewing events to avoid similar issues going forward.”