The potential leaders gathered in Sportslink in Santry today to have their photos taken, meet the team of OT experts and get their fitness assessments to find out who will be going forward to the 2017 series of Operation Transformation.

There was a great buzz about the place as previous leaders Gerald Keane, Brenda Donohue and Alan Mullen sat down with Ray D'Arcy to talk about their experiences on the show. Gerald kicked things of with some advise to the future leaders to "go and enjoy it".

"I'm looking at you guys and I think you all look great anyway but I was struggling. Tying my laces was a big problem, going up the stairs, getting in and out of a car, so when they asked me to do it, I only took seconds to say yes and it changed my life!

Gerald lost just under two stone on the show and since it ended he's lost a further one stone and three pounds. Brenda Donohue says her journey hasn't been quite so straight forward as bad habits started to creep back into her life once the cameras left her home.

"There is nothing scarier than standing up in front of half a million people in your knickers with Kathryn Thomas looking gorgeous beside you. I mean that will focus the mind pretty quickly and that will make you want to hit your target, there's no question of that! So once the cameras went there was that relief of not having to hit a target"

Fortunately, Brenda got back on track with her OT plan and says she feels younger and more energetic than she did when she was in her thirties! The radio presenter lost just over a stone and says she can't wait to have the new leaders to follow and spur her on.

Alan Mullen was a leader on Operation Transformation two years ago and viewers will remember his particularly emotional and honest journey. At twenty-one years of age Alan was twenty-seven stone and says he was "on his way to the graveyard". We caught up with Alan to find out how the past two years have been and exactly how much weight he's lost!

"My progress with the show since it finished has been absolutely great, I've lost seven stone, I started at twenty-seven stone and now I'm down to twenty stone."

Listen to the full show with Ray D'Arcy and the Operation Transformation gang here:

Keep an eye on RTÉ LifeStyle over the coming weeks as we will have more interviews, photos and healthy eating tips from Kathryn, Ray and the OT gang!