"He looked very relaxed, but other punters did clock who he was and took a couple of pictures."
Another source said Fury was a 'gent' and was happy to sign her Nando's napkin.
With an average male needing to consume on average 2,500 calories a day to maintain his weight, Fury will have to work hard in the gym after his Nando's binge.
In 2014, Olympic swimmer Ryan Lochte shared an image of his typical 10,000 calorie meal while Michael Phelps once claimed to consume 12,000 calories a day - before later saying it was a myth.
Lewis James, a lecturer in nutrition at the UK's Loughborough University, told CNN: 'People like Ryan would be training for very long periods at a time, (meaning) they have long periods of their days when they don't get any food in at all.
"I would expect someone like Ryan Lochte to have 10,000 calories in a day,' he said, adding, 'but in one meal it sounds like quite a lot."
Meanwhile, Fury - announced on the 12-man shortlist for BBC Sports Personality of the Year along with F1 champion Lewis Hamilton and Davis Cup victor Andy Murray - is not expecting to win any awards as he believes he is 'too controversial and outspoken'.
"There's no point me thinking about it. I'm not bothered. If I don't win any award, I've never expected to win one anyway," said Fury but added: "Has anyone else beaten a super-champion this year? Taken him out? Taken away all his belts? Who's done what?
"So Lewis Hamilton has won the F1 championship and Andy Murray has won the Davis Cup. Hamilton can win a race and it doesn't mean anything. Murray can win a tennis match and lose a tennis match and still have his popularity. But who beat Wladimir Klitschko, the man they said couldn't be beaten? Answer: Tyson 'Too Fast' Fury."
FURY'S FEAST
16 double chicken wraps
Calories: 11, 584
5 corn on the cob
Calories: 3,144
6 portions of chips
Calories: 720
CALORIE GUIDELINES
Male: 2,500 calories a day
Female: 2,000 calories a day
- Daily Mail
