Deborah Hadley (32) from Tipperary finds the 5:2 Diet fits in with her busy lifestyle looking after her three children under 10. She's been so pleased with her 'fast' meals she's even started sharing them on her blog, Debalicious.com. She says:
"I've been on and off diets since I first went to Weight Watchers about 10 million years ago.
"At my heaviest I weighed over 300lbs, just from eating badly and after having three children but I got down to 235 and now, after starting the 5:2 Diet in February, I'm 220lbs (15.7 stone). I've still a way to go but I feel like I'm on the right track and that's even with taking a month off the diet to move house!
"The great thing about it is that it's not too restrictive. I'm not cutting anything out and the fast days feel like something I could do for the rest of my life.
"On a fast day I'll usually hold off on breakfast until noon when I'll have an omelette using one whole egg and two egg whites and filled with vegetables. Then dinner would be a chicken salad.
"I used to think I'd wake up ravenous the following day but actually I've ended up eating less and got over the 'last supper' mentality of loading up the day before a fast.
"I feel better and have more energy and it's easy to work round the rest of the family because the fast days are flexible.
"Eating normally on the feast days almost feels like cheating because I'm not depriving myself of anything but still losing weight – it's great!
"It sounds like such a cliché but I really feel this isn't just a diet but a lifestyle now for me."
'I had to give up after three weeks – I didn't feel well'
Mum-of-two Laura Davies (37) from Wicklow tried the 5:2 Diet for three weeks before persistent nausea made her ditch the approach. She says:
"I'm 5ft 3ins and 10 stone which means my BMI is 25, so I don't have too much to lose but I'd love to get it into the healthy range.
"When I watched the BBC Horizon documentary Eat, Fast and Live Longer featuring Michael Mosley last year, I thought 'that sounds great!' and promptly bought his book and joined a Facebook group.
"But I had to give up after three weeks. On the days after the fast days, when I started eating normally again, I had terrible digestion problems that on some occasions had me running for the bathroom with an upset stomach.
"I just didn't feel very well. During the 500-calorie days I really obsessed about food and deliberately planned not to do too much and subsequently felt like I wasn't living my life.
"I also probably over-compensated on my 'feast' days, meaning I didn't lose much weight.
"I'm a great believer in listening to the body and on this occasion my body was saying to stop.
"I had another go at fasting after that, doing the Fast Five plan by Bert Herring where I only ate during a five-hour window, usually 2pm to 7pm, to give my digestion a 19-hour break and I lost half a stone on that, but then put it back on while on holiday.
"To be honest I'm not convinced. The evidence about fasting is inconclusive and some people say it can raise your cholesterol. I'm trying to exercise more now and focus on being healthy.
"In the past I always would have been looking for that 'quick fix' but I think the reality is everything in moderation."
'The morning after a fast I feel my body and mind function better'
Mature student and mum-of-one Farrah Tayob (28) from Dublin has lost almost a stone in five weeks on the 5:2 plan – but warns that it can be addictive.
"After having my son Alexander, who's three-and-a-half, I struggled to lose the baby weight.
"I was never into dieting and would never have touched Atkins or Dukan. But my personal trainer kept talking about the 5:2 Diet and how I should try it.
"In the past five weeks alone, I've lost 12lbs. I've also been doing a lot of weight training.
"Generally my fast days are Tuesday and a Thursday. I make sure I'm busy so I'm not tempted to pick at food.
"Typically, on a fast day, I'll have an egg-white omelette with mushrooms and spinach for breakfast and a fillet of salmon with steamed broccoli and salad for dinner.
"I don't know if I'd even really call it a fast because you're still eating.
"I also drink coffee because it's quite a good appetite suppressant, and lots of water and green tea.
"On my non-fast days, I'm healthy – but I'll still have dark chocolate.
"It hasn't affected my social life because I just do the fast days when I don't have to meet people. I'm not going to go "the cinema where I'll be tempted to have popcorn on a fast day, for instance.
"To be honest, I don't really tell people I'm doing it because they just say: 'You're tiny – what do you need to be doing that for?'
"For me, I've found the health benefits more of an incentive than the weight loss. I used to suffer badly from migraines and they seem to have gone.
"The morning after a fast, I just feel so bright – I actually feel like my body and mind function better.
"I've recently gone back to college to study psychology, so I find I'm much more focused and disciplined.
"The one minus is that it can become addictive.
"A couple of times I thought: 'Oh maybe I'll do three days fasting this week!'
"But I know if I lose any more weight I'm not going to look good.
"Now I plan to just do one fast a week to maintain the results."
We ask the experts: Well, does it work?
Yes: 'It improves overall health'
Fitness instructor Carrie Skinner has been intermittent fasting for the past two years and believes it can work for others too. She says:
"The 5:2 Diet, I believe, is unfortunately named. We all know that diets don't work. They cause stress, aren't healthy and ultimately result in weight gain in 95pc of dieters.
"The 5:2 'diet' is not a diet: it's a simple way of eating that will improve overall health. Weight loss is merely a happy side effect for many.
"Of course, the 5:2 way is not for everybody – type 1 diabetics, anyone with history of eating disorder, those already very lean, children, and pregnant women are not advised to follow the plan. Fast days are made easier by planning what and when to eat and by preparing meals in advance – for example, batch cooking and freezing portions.
"As a fitness instructor, I won't recommend a diet to clients that I haven't tried myself. Intermittent fasting was something I discovered experimentally and have kept up for the past two years.
"On fast days, I am alert, focused, have more energy, and feel great. On non-fast days I still prefer to eat nutritious healthy food. Intermittent fasting is not a new 'fad'. It has been around for centuries. It is safe and just as effective for working mums as it is for athletes. On the 5:2, I am weight-stable and feel healthier than ever."
No: 'I wouldn't advise it'
Sports nutritionist Daniel Davey isn't convinced that intermittent fasting is a long-term solution to promote healthy eating. He says:
"If the message is that you can eat what you want five days a week so long as you drop to 500-600 calories on two days then no nutritionist worth their salt would agree with that concept.
"To just limit calorie intake on two days a week isn't correcting behaviour around making the right food choices.
"It's important people learn about the right foods to eat and how to create meals, like the recipes I post on Twitter @foodflicker, rather than becoming fixated on counting calories.
"I think a lot of people want to believe in a 'wonder diet' and actually end up over complicating matters counting calories, fasting or only eating certain foods.
"The reality is quite simple, you need to match your nutritional and energy needs to the amount of energy you expound and stock your cupboards and fridge with whole foods, not processed food or refined carbohydrates.
"Suggesting that people can eat whatever they want so long as they fast twice a week is certainly not an approach that I would suggest and definitely not one I'd let someone embark on without supervising a weekly food plan or after exhausting other approaches that focus on making positive changes to their lifestyle."