By Ray Dunne
BBC News Online health staff
He spent 44 days suspended in a Perspex box in central London.
David Blaine spent fives days in hospital after the stunt
He had eggs thrown at him, golf balls aimed at him and women exposing themselves in front of him.
By the end of it all, he needed five days in hospital to recover.
To many, David Blaine's recent stunt was nothing more than a blatant, albeit successful, bid for publicity.
To others, it was a death-defying, enthralling exercise.
But for one doctor at least, it has been an unintentionally worthwhile medical experiment.
What's more, it could change the way thousands of sick people are treated every year.
Professor Jeremy Powell-Tuck is one of the UK's leading nutrition experts. He was drafted in to provide medical care and advice to David Blaine when he finally walked out of his box.
It was his job to ensure the world-renowned illusionist's first meal didn't kill him.
"It is a real risk," says Professor Powell-Tuck, who is based at Barts and The Royal London NHS Trust.
"We call it re-feeding syndrome. Due to a lack of food, the intestine becomes less tolerant to food.
I like David Blaine. It would be a very boring world if someone isn't allowed to do something stupid every once in a while
"This can lead to diarrhoea and it can cause the stomach to become very big.
"But the biggest problem is that levels of insulin in the blood go up after having been quite low.
"This can drive some important minerals out of the blood and into the body's cells. This can cause fits and sometimes even death."
Unsurprisingly, David Blaine was kept under close medical supervision throughout his time in hospital.
"David was admitted to hospital on the Sunday evening after his stunt and he stayed until Friday," says his doctor.
"We kept a close eye on him. His stomach did dilate and he did develop ankle swelling, both of which are common in people who start re-feeding.
"But by and large, he recovered as we expected."
'Sceptics are wrong'
When David Blaine left his temporary riverside home, he was greeted by a 10,000 strong crowd of adoring admirers, intrigued onlookers and sceptical spectators.
Many questioned whether the illusionist's stunt was simply that - an illusion.
Had he really gone without food for 44 days, as he claimed, or had he secretly consumed nutrients through his water supply, something he strongly denied.
The Blaine box became a popular tourist attraction
After all, for a man who spent over seven weeks in a small Perspex box without food, he looked remarkably well.
Yes, he had lost some weight but he didn't appear to be at death's door as some had predicted.
According to Professor Powell-Tuck, tests on David Blaine suggest the illusionist had indeed deprived himself of food.
"I was very cynical at first. I knew he was an illusionist and I knew he was a very good illusionist.
"But he made it clear to me that the trick this time was that there was no trick.
"In fact, the weight loss he suffered while he was in the box was more than he predicted. That was probably due to the cold nights."
David Blaine lost almost 30% of his body weight during his stunt. He went into the box weighing 96kgs and came out weighing 70.5kgs. Despite appearances, he was suffering from malnutrition.
"David didn't look very undernourished but he was. He had lost almost a third of his body weight," says Professor Powell-Tuck.
"I think it has some very important lessons for us. It shows that if you just rely on eyeballing people then you tend to underestimate the amount of undernourishment around.
"This is a major problem for hospitals, GPs and nursing homes. But if you don't ask the right questions, then you can miss it.
This could help us to improve nourishment in hospitals
"This is something I have been banging on about to medical students for years. They don't tend to take it in. In that respect, I think David Blaine provides a very nice lesson."
Professor Powell-Tuck is still in touch with his American patient. He is currently awaiting the results of the latest medical tests, which he expects will confirm David Blaine is on the road to a full recovery.
Interestingly, Professor Powell-Tuck believes the results from these and other tests can be used to help other people with malnutrition.
"Malnutrition is a serious problem, particularly in hospital. A combination of disease and malnutrition often serves to put patients at risk.
"What David Blaine has done is to allow us to see what pure undernutrition is like in the absence of disease.
"This could help us to improve nourishment in hospitals."
Despite his initial cynicism, Professor Powell-Tuck now classes himself among the thousands of new David Blaine fans.
"I like David Blaine. It would be a very boring world if someone isn't allowed to do something stupid every once in a while."