David Blaine has begun feeding for the first time in 44 days. Doctors at the London Independent Hospital have started him on a nutritional drink packed with vitamins.
The illusionist is allowed only small quantities at a time as immediately resuming normal eating habits apparently could kill him.
He has so far drunk about a pint of the liquid. Blaine suffered a sleepless first night out of the box beset by stomach cramps.
Initial blood tests have proved satisfactory, but doctors are continuing to monitor his condition during what his spokesman described as a critical phase in the magician's recovery.
His heart is being constantly monitored and he is under 24-hour nursing care. His weight is 11 stone - nearly four stones lighter than the day he entered the box.
Blaine is under the care of gastroenterologist Professor Jeremy Powell-Tuck at the private hospital in east London. A spokesman for Blaine said: "Continuous checks are being made on how his body is accepting and coping with this nutritional therapy in order to prevent complications arising.
"Professor Powell-Tuck is expecting to maintain a series of assessments, including blood tests, over the coming days as Mr Blaine gradually recovers.
"It is currently impossible to predict how long Mr Blaine will be required to remain in hospital, or to determine any long-term effect, though Mr Blaine is being continually monitored."