WBO featherweight champion Scott Harrison has withdrawn from his title defence on Saturday and vacated his title, his father Peter says.
Harrison (left) has withdrawn from his title defence against Cook
The Scottish fighter, 29, was due to fight Dagenham's Nicky Cook at the Excel Arena in London.
Peter Harrison said his son was unable to make the weight and would now vacate his title "on medical advice".
"Scott was unable to get under 9st 7lb and - on medical advice - was advised not to take the fight," he added.
Harrison spent five weeks in a Spanish jail on assault charges and was released on 13 November amid doubts over whether the fight would go ahead.
But the British Boxing Board of Control ruled the fight could go ahead after Harrison underwent medical tests.
Frank Warren has been slow to tell the people that the fight is off
Peter Harrison said his son had trained three times a day over the weekend in a bid to get to the featherweight limit of nine stone.
But, after consulting with Dr Niall MacFarlane of Glasgow University, his father decided Harrison would not make the weight in time for the bout against Cook.
Peter Harrison added: "Promoter Frank Warren was notified on Sunday of Scott's difficulty in making the weight.
"Frank Warren came back to Scott's manager Barry Hughes on Tuesday with the offer to fight Cook at 9st 6lbs.
"The fight was really important to Scott but there was no way he was going to get down to 9st or 9st 6lbs.
"We've known it's been off since the beginning of the week. Scott needed this fight. It's been well-documented in the media that Scott has to pay his income tax and he was going to pay it off with this fight.
"But when you're talking about somebody's life you have to make the right decision and I feel Team Harrison has made the right decision."