Behind the glitz and glamour, Strictly Come Dancing is hard work.

Celebrity contestants train for up to 10 hours a day, especially in the final weeks of the competition.

This gruelling schedule has led to some astonishing body transformations, with stars dropping dress and shirt sizes.

Here we run down some of the BBC One show’s most memorable.

Lisa Riley

Strictly Come Dancing
Lisa Riley (Guy Levy/PA)

The former soap star and Loose Women panellist underwent possibly the most dramatic weight loss journey on Strictly.

The actress, 43, said she lost 12 stone during and in the wake of the show, after also giving up alcohol.

Riley, who played Emmerdale’s Mandy Dingle, competed in 2012.

She later said: “I went in there this big fat girl and I refused to be the comedy turn. I have been to drama school, I have rhythm.

“I was going to show everyone not to underestimate women like me and that even if you are big you can dance.

“The whole experience was amazing.”

Mark Wright

Strictly Come Dancing 2014
Mark Wright (Guy Levy/PA)

The former Towie star, 32, lost over a stone during training with Karen Hauer.

But the Essex-raised former footballer and reality TV star was not completely happy with his new image.

“My body has changed but I like being trim,” he told The Sun at the time.

“I think I have lost about a stone.

“A lot of it is muscle because I used to do weights but don’t any more.

“I don’t feel as if I want to go out now and show off my body.”

Kate Silverton

Strictly Come Dancing 2018
Kate Silverton (Ray Burmiston/PA)

The BBC newsreader, 49, joked she had been enrolled in the “Aljaz school of weight loss”.

After weeks on the show the mother-of-two, who married former Royal Marine Mike Heron in 2010, was even able to fit into her wedding dress.

She said the show’s costume department had to take in one of her outfits twice.

Ed Balls

Strictly Come Dancing 2016
Ed Balls (Guy Levy/PA)

The former Labour politician, 52, joined Strictly shortly after losing his parliamentary seat in the 2015 general election.

He fared better on the small screen, making it to the 10th week with his partner Katya Jones before being eliminated.

He said he had lost almost a stone in five weeks, and Balls joked his wife Yvette Cooper MP had only wanted him to join up for the show’s weight loss potential.

Gemma Atkinson

Strictly Come Dancing Launch 2017 – London
Gemma Atkinson (Matt Crossick/PA)

The soap star revealed she had been told she was too muscular to take part in the competition but used her increasing svelte physique to storm through to the final.

“I’m not your usual petite dancer’s physique,” the 34-year-old said during a press conference with fellow finalists Debbie McGee, Joe McFadden and Alexandra Burke.

“Everyone said to me: ‘There’s no way you’ll be able to do it because you’re too muscular or too much of a tomboy’.”

Atkinson’s stint on the show won her more than just runner-up.

She now shares a daughter, Mia, with Spanish-born dancer Gorka Marquez.

Faye Tozer

Strictly Come Dancing Launch 2018 – London
Faye Tozer (Ian West/PA)

The Steps star worked through a gruelling training schedule alongside her professional partner Giovanni Pernice, dropping a dress size.

She told New! magazine: “I’ve definitely dropped a dress size.

“I was between a size 10 and a size 12 and now I’m a size 10.

“I thought I was fit before but you’re literally on your feet for at least six hours a day.”