Dubai resident Selina Waterman-Smith has told how she put on half a stone due to the 'horrendous' food on the hit BBC1 TV show.
The Apprentice contestant's weight shot up from 9st 2lbs to 9st 9lbs during filming because she was living off pre-packaged sandwiches and crisps and biscuits.
She said contestants often had to make do with a Pret A Manger sandwich for breakfast as they rushed between tasks.
And when they were living together in the £11 million contestants mansion they were expected to eat processed ready meals packed with chemicals.
Selina, 32, said: "The food on The Apprentice was horrendous. We were living off junk and fast food most of the time and grabbing sandwiches when we could in-between tasks.
"It didn't bother a lot of contestants but I have various food intolerances and it became a very big issue for me over the course of the filming. They did do catering at the house on busy task days which wasn't too bad but they definitely could have done more.
"I was slammed in the boardroom for yawning and appearing to be tired on one of the tasks. The fact is, I was exhausted because I wasn't eating properly and because of my chronic illness ME (Myalgic Encephalomyelitis, a long-term illness which can cause fatigue).
"We were not allowed to leave the house in-between tasks and I asked producers to provide me with Tupperware so that I could prepare my own meals so I wasn't having to live off Pret sandwiches during the day.
"But it took them several weeks to get me the Tuppaware so I could control my meals better."
Selina has an intolerance to grain, egg white and dairy products and a lower gut motility disorder which means she has to be very careful about she eats.
A team of four researchers lived with the candidates in the Bloomsbury mansion which costs £17,000 a week to rent. They were there to supply food and sort out any problems.
She said: "I flagged up these medical issues before the show and they were a little slow to respond. A lot of the food we had at the house was good but it got eaten very quickly. I understand the difficulties of feeding someone with my issues during a very busy filming schedule but it just wasn't right for me.
"As more people got fired and there was less people to look after they did make more effort to cater for us during tasks, but it was a far cry from my usual healthy routine."
Single Selina, who runs her own creative production company in Dubai where she lives, was determined to get back into shape after filming and enrolled at No 1 Boot Camp, a tough weight loss retreat loved by celebrities where all the trainers are ex-Military.
She lost the 7lbs she put on while filming the Apprentice and now has the body of her dreams. Blonde Selina said: "I had a brilliant time and lost 7lbs in a week. The food was amazing.
"We were doing some really intense work-outs and surviving on 1,000 calories a day thanks to the fantastic, nutritious food prepared for all the campers. I am quite short at 5ft-and-half-an-inch. If I put on weight, I always struggle to lose it again.
"What the camp taught me is that if you eat well and exercise a lot, you get fitter but you don't get thinner. The way to lose the weight is to really look closely at they way you fuel yourself and adjust your nutrition.
"The trainers taught me to do that and I was able to completely embrace a whole new lifestyle."
Selina is planning to go back to No 1 Boot Camp in the New Year to lose a further half-a-stone.
No 1 Camp is a big favourite with celebrities and Vanessa White from the Saturdays and Ashley Roberts from the Pussycat Dolls both recently lost weight at the camp.
A spokesperson from The Apprentice said: "Selina's dietary requirements were consistently and fully addressed by the production team throughout filming. We take our duty of care for all candidates very seriously."