Mastermind champion Fred Housego has a new specialist subject - dieting.
The taxi driver is more famous for his brains than his bulk, but decided to act after his wife warned he was eating himself to death.
Fred, who famously won the BBC quiz in 1980, used mind over matter to drop six stone in just six months.
He's now a third of the man he used to be, tipping the scales at 12 stone.
Once the owner of a huge 50in beer belly, a new eating and exercising regime has seen his waist size fall by 16 inches.
He cut out the eight pints of ale he glugged down during pub quiz nights and swapped his favourite snacks of crisps and cheese for salads.
He also decided to join a gym to balance his sedentary lifestyle of driving, reading and pub-going.
He said: "My wife Pat said, 'You have got to stop - you are killing yourself'.
"Now I eat loads of fruit - my cab is like a greengrocer's. I have much more stamina."
Fred, who celebrates his 63rd birthday on Thursday, had extra cause to shift the pounds as he has diabetes.
Sufferers who are obese are advised to lose weight to reduce the risk of complications such as blindness, kidney failure, strokes and heart attacks. Weight loss can also help control the condition as it reduces insulin resistance.
A recent study by the University of Surrey, the Royal Free Hospital and University College London showed that people with type 2 diabetes who are obese could be reducing their life expectancy by up to eight years.
Fred, who lives in Pevensey Bay, near Eastbourne, became an overnight celebrity after his Mastermind win.
Having left school at 16 with only one O level he worked briefly as a postman before becoming a London cab driver, reading at every opportunity.
In 1980, he won a place in the nation's affections when he triumphed in the legendary black chair with his specialists subjects: Henry II of England, Westminster Abbey and The Tower of London.
The win launched a broadcasting career which included appearances on Blankety Blank, The Pyramid Game, The Six O'Clock Show and This is Your Life.
He also hosted an all-night radio phone-in show on LBC during the 1990s.
More recently he has been among the fine minds appearing on BBC Radio 4's Round Britain Quiz.
Have you or someone you know lost as much weight as Fred? Tell us your stories below or call Rachel Wareing on 01273 544547.
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