Actor is hoping he’ll dance his way to being a healthy, slimline shadow of himself.
“I’m 20-odd stone,” Mark told The Sunday Post. “I’m happy with myself but I do have health concerns.
“I’m 47 and the older you get the harder it is to keep the weight off.
“I’ve never wanted to diet. I think you have to change your lifestyle and get exercise, which is what I find hard.
“I haven’t set a target, I just want to lose as much as I can.”
Mark, whose mum is from Ayrshire, has already made inroads, dropping three trouser sizes since taking the lead in the hit musical Hairspray.
His last Scottish performance was at Aberdeen’s His Majesty’s Theatre last night and he finishes up in Norwich next Sunday.
It’s meant that pro partner Iveta Lukosiute has been clocking up the miles to spend seven hours a day on their opening tango before his nightly shows.
Mark’s big concern over Strictly was the impact on kids Archie, 15, Grace, 12, and eight-year-old Fig.
“My wife Sarah told me if I wanted it I should just go ahead and do it. But my worry was kids saying nasty stuff to my kids about me and how I do. I really don’t want that to happen. I guess it’s part and parcel of the show, though, and they’re all really supportive.
“I know Strictly have their set characters and I’m probably the chubby comedian.
“But Iveta told me she wanted people to smile at me actually doing the dance rather than laughing at me because I can’t.”
Mark is already a big favourite north of the border from playing hapless teacher Chalky in Greenock-shot Waterloo Road.
The school drama has Strictly previous with ex-regular Chelsee Healey going all the way to the final.
“I’ve had so many texts and calls from everyone saying they’re right behind me,” he adds.
Meanwhile, former Strictly favourite Russell Grant has called Flavia Cacace “the daughter I never had”.
He’s admitted her exit will be a big blow to the show. Flavia, who won last year’s series with Louis Smith, is one of several high profile pros no longer around, including partner Vincent Simone and Erin Boag.
“She will most certainly be missed, she’s absolutely amazing,” says 62-year-old Russell. “To me Flavia is family.”
The unlikely duo got all the way to the Wembley extravaganza two years ago, with Russell’s highlights including being fired out of a cannon. They became so close Russell revealed that Flavia turned to him for advice about Olympic gymnast Louis.
“It’s well documented that Louis had ADHD and she’d come to me to chat about it. Wouldn’t you if you had a best friend you could trust and rely on? Having done Strictly the year before I knew exactly what it entailed and how, even for an Olympic champion, it takes absolutely everything.
“I wanted them to win from the word go and burst into tears at the final.”
Such is the bond between Flavia and Russell they have produced their own dance fitness DVD.
“Our Zalza DVD sold 20,000,” said Russell. “So we’ve just filmed a Christmas special.”
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