As Operation Transformation returns to our screens for its 10th season tomorrow (8.30pm, RTÉ One), we meet the five inspirational people that will be guiding the nation towards better health in 2017.
Mairead Redmond (22) New Ross, Co Wexford
Height: 5ft 5in
Weight: 16st 5lbs
As a child, Mairead remembers her mother sitting her down and telling her she'd have to lose weight as they were struggling to find a communion dress that fit her.
"I think I'm still in denial and a little bit of shock about taking part in Operation Transformation, it's very surreal. I wanted to apply last year, but when I talked to one of my friends, she put me off doing it because she pointed out how busy I am. I am still really busy, but if I don't do it now, I never will."
Mairead works as a pastry chef and chocolatier while simultaneously studying for a degree in business and says she's one of many young people that just don't take the time to look after themselves in between work, college and a social life. She loves her work as a chocolatier, but it's a tough profession for someone trying to lose weight. "I'm kind of like Willy Wonka! I've always had a sweet tooth, but working in the business I'm both very snobby about the kind of chocolate I eat and constantly picking at it! But the biggest change for me will be the exercise - I don't mind doing it, it's just trying to find time for it. For me it's not a chore - I need someone to give me a kick up the arse. I just want to lose weight, be happy and healthy."
Chris McElligott (46) Dunshaughlin, Co Meath
Height: 5ft 7in
Weight: 17st 11lbs
Some 16 years ago, Chris's right leg was severed below the knee in a road traffic accident and he's been wearing a prosthetic leg ever since. A former international footballer, he now works for the FAI's programme for disabled children and the sport is still a huge passion of his. "The main reason I applied for the show is because I want to get back playing football. I also didn't want to have the idea in my head of having a heart attack while working because of my weight."
Chris's weight makes his everyday mobility more of a struggle, putting undue pressure on his prosthetic limb. "I haven't really had to diet much in my life - I could eat what I wanted and was able to burn it off with the training I was doing, so for me it didn't matter, or so I thought. But since losing my leg, I've realised that the little pleasures in life like food have caught up with me and are now making it so much harder to lose the weight I've gained.
"I think the thing that will keep me going when I'm saying to myself 'is this really worth it?' would be the dream of getting back playing football, even as a recreational game. But I would love to push myself to play internationally again and that will be my motivation. My goal is to be healthier and lose as much weight as I can, and to have the tools and skill to carry on after the show."
However, he's under no illusions about the difficulties that lie ahead for him. "I'm actually not too nervous, but if I was to choose one thing to be nervous about, it would be standing in Lycra shorts in front of the nation!"
Marie Grace (32) Pallasgreen, Co Limerick
Height: 5ft 5in
Weight: 14st 2lbs
Part-time hairdresser Marie says she applied for the show because she lost her confidence and motivation. "I have piled on weight in the last couple of years and just couldn't seem to motivate myself to do something about it. I bought a dress for my daughter's christening about a month before the event and by the time it came to the day of it, the dress wouldn't fit me. That made up my mind about it all."
Marie has three-year-old Lily Mai and baby Daisy, but she and her husband Fergal lost their second daughter days after she was born in 2014. They were delighted when Daisy arrived nine months ago, but she has severe acid reflux and regularly screams in pain throughout the night. This means Marie hasn't had a full night's sleep in months.
"I need to get out exercising with my family. I really haven't done anything at all with them since I had Daisy and at this stage, I need to improve my health and fitness for them. I think what will keep me going is that I know other people will be following me and I will be determined to do it for them.
"I watch the show every year and while I'm nervous about taking part, I'm also absolutely thrilled. I'm excited about getting going with the exercises and plans and can't wait to see the end result."
Sean Daly (25) Clondalkin, Dublin
Height: 6ft 1in
Weight: 23st 12lbs
Sean is undertaking his Operation Transformation mission for his family. He lives at home with his mum, dad and brother, and they've all been a huge support system to him since he came out as gay several years ago.
"I can't put into words how proud my friends and family are of me already and they're all so happy for me. I'm doing this for my family."
Upset with his weight, Sean had been considering going to Poland to have a gastric band fitted before he got the call from RTÉ. He says he's never been on a real date and doesn't know how someone else could love him if he doesn't love himself.
"I was unhappy with how I looked and wanted a change in my life. I just felt this was my time to change and the show would give me the tools and help I need. I need to change my habits and give up smoking too."
Yvonne Keenan Ross (48) Carlingford, Co Louth
Height: 5ft 6ins
Weight: 16st 8.5lbs
Yvonne runs a café, but her family has been through a lot in recent years. After six unsuccessful rounds of IVF, she and her husband Stephen finally got the family they wanted when Luke and Karla were born. However, five years ago, Stephen was diagnosed with stomach cancer. Thankfully he's free of the disease now and Yvonne wants to focus on her own health and well-being. "I've wanted to lose weight and have been on a diet for about 20 years, but this September we were on holiday and there was a full length mirror on my side of the bed. I realised I was fatter than I thought I was and it was time to do something about it."
Yvonne was inspired by Celebrity Operation Transformation star Elaine Crowley (above). "I followed her food plan for a few weeks. Now, I'm looking forward to January for the first time in years. I think it's a fantastic opportunity - there's nothing like a bit of public humiliation to motivate you! I'm nervous about juggling everything: work, the kids, the show, cooking, exercising… I'm not a very organised person, so this will be a challenge.
"But I'm doing it for myself first and my children. I want to be fit and healthy for them and have energy to do fun stuff with them. They've been through a lot with their dad being so sick for so long so they deserve me to do the best I can and be the healthiest I can."