The reality star will be seen stripping off on the special show later this month, hoping to raise awareness of life-saving cancer checks.
It follows Demi being diagnosed with thyroid cancer in May, revealing in a chat with FUBAR Radio tonight that she's had to undergo multiple surgeries and radiation treatment.
Chatting to hosts Bobby Norris and Stephen Leng on Access All Areas, the 23-year-old shared: "It has been difficult, especially with my mental health. Being in the public eye in general is difficult and straining at times, let alone dealing with my illness and stuff in private as well."
Demi told the pair that taking part in this year’s Strictly The Full Monty has been one of the best experiences of her entire life.
"To be around people that have gone through it and have similar experiences, for me it was like a form of counselling," she said. "I feel like I’ve got more comfort and understanding for what I’ve gone through since filming The Full Monty than I have from friends and family because sometimes it’s like, ‘how do you talk about it to people?’”
Starring alongside the reality star on the ITV show is fellow Love Island alum Teddy Soares, Blue singer Duncan James and EastEnders actress Laila Morse. Talking about her fellow cast members, Demi revealed: "We literally bonded so well because all of our stories brought us together.
"I think the common denominator in most of our stories was that we weren’t referred quickly enough, or our cancer wasn’t spotted quickly enough, so we all bonded in that sense.”
Demi admitted she was nervous about taking to the stage, explaining: “People say to me, ‘You’ve been in a bikini on TV, you’ll be fine’. But I’m still subconscious, I’m still a young girl.
"You’ve got all this pressure from Instagram and social media on what you’re supposed to look like, so for me to still get my bits out and all my wobbly bits, it’s still scary”.
Meanwhile, Demi spoke candidly about her diagnosis and how the past year has changed her: “I feel like I’m a different woman now, I feel like I’ve done so much growing up this year and I’ve had to mature really quickly.”
She added: “I’m literally just waiting on my results actually to find out if I’m cancer free and if it’s gone, so fingers crossed I’m on the other side of it now.
"I keep describing it as like a dark cloud. So as much as I’m getting on with my life and am excited for Christmas, it still lingers over you thinking like ‘what if’.”
"I really hope that I hear before the end of the year, I just wanna know. I think the waiting is the hardest part."
You can listen to the full interview on the FUBAR Radio website here.
Strictly The Real Full Monty will air on ITV at 9PM on 13 and 14 December.