Can the 5:2 concept be applied to all parts of life? We review the book that claims this popular ratio could change everything

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Many experts in the health field would agree with the idea that life is about moderation, and doing things right 80 per cent of the time instead of aiming for 100 per cent perfection is plenty to lead a life of wellness. Without getting too stuck on figures, this mathematical stance is not dissimilar to that of the 5:2 diet , the 'fast diet' which has swept the nation's dinner tables over the past year.

Based on the simple formula that sees you fast for two days (eating no more than around 500 calories) and eating 'normally' for the other five, the diet has become a way of life for many - just read GTG's forums  or community comments  to get an idea of how many are converts. But what started as a study, and then a book, by Dr Michael Mosley, has made way for all kinds of interval-based activities which reap so many health benefits that it's impossible to argue (though you do wonder how this has only just come to light). High Intensity Interval Training  (or Fast Exercise, as Mosley penned it in his recent bestseller) was next on the list as the intermittent lifestyle feature to work mini miracles, and now Emma Cook, editor at The Guardian and parenting author, has extended it further by taking the premise of the 5:2 and applying it to all aspects for life in order to be happier, healthier and perhaps even wealthier. Enter, 5:2 Your Life.

Can the 5:2 concept apply to your life?

While it's easy to see that jumping on the immensely popular 5:2 bandwagon is a recipe for success (Mosley's co-author Mimi Spencer  has made her name with a successful recipe book, soon to be followed by a second), Cook's self-help paperback is not a how-to guide for intermittent fasting. A 5:2 diet convert herself after dropping 13 pounds in four months on the regime, Cook then noticed that 'one small change was a catalyst for so many others', and began applying the concept of the 5:2 to other parts of her life. The author comments that we continuously graze on all kinds of matter - food is just the beginning. Tweeting, texting, shopping, worrying; they all take up our time and are all things we do to excess. By taking time out from each just a couple of times a week, Cook realised that she could regain control and teach the art of moderation to her whole family.

The 5:2 has never been about deprivation; it doesn't require endless amounts of willpower because you spend the majority of the time behaving how you like. It's just a smidgen of the week that involves cutbacks and focus, making it a way of living that is not simply a fad or too much of a struggle to maintain. Cook's book takes this principle and applies it to eight areas of modern life; drink, fitness, finance, productivity, screen life, relationships, worry, and environment. She purposefully chose topics that are all healthy in moderation - overdo it and you'll be stressed, but keeping on an even keel is a necessity for happiness.

Cook's reasoning is hard to dispute. Beginning with her tales of success with the 5:2 diet before going on to explain why the ratio is so well fitted for life, she includes examples as early as, er, God, who created the world in just six days and took a break, of course, on day seven (the 6:1, as many 5:2 dieters switch to once they've reached their target weight). But a stronger argument is that of Henry Ford, the car manufacturer who spent years of research on deciding the optimum working week schedule for productivity, and rested on the idea of 40 hours over five days, with a two day break. The weekend as we know it was born and became a time to rest, to play, to reflect. Was Ford the original 5:2 advocate? Mosley might have something to say about that, but it certainly backs up the point.

From the drinking chapter where it is explained, with expert help, that two consecutive days off the booze is a must in order for your liver to recuperate, to the section on getting on top of finances by tightening the purse strings twice a week, Cook details her thought process throughout and starts every chapter with an explanation of how she was before she became a 5:2 devotee. It feels a little like she's reassuring us 'I was normal and a bit of a mess once, just like you!' but it has the effect of that little voice in our head piping up to say 'Me too!' when she speaks of cracking open a bottle of wine as a daily habit or mindlessly spending on items she doesn’t quite need. It's all relatable, and though the idea of taking days off from all parts of your life is daunting, bit by bit it starts to make sense.

The book is enriched by scientific studies, first person accounts of applying the methods to everyday life, and the agreement of experts in all fields agreeing that the 5:2 ratio is a sensible place to start. Even GTG's favourite personal trainer Steve Mellor  of Freedom2Train pops up with his explanation of High Intensity Interval Training (HIIT) in the fitness section, endorsing the combination of HIIT and the 5:2 concept because it is 'realistic'. It's hard to argue, too, when he says his common guilt trip for clients is: "If Barack Obama can manage to exercise every day, you can certainly do it twice a week".

The final chapter on the environment doesn't sit quite so snugly with the rest of the book; it's less personal and harder to connect with, but requires you to face up to your carbon footprint as well as evaluate how wasteful your habits are - whether it's losing money by insisting on driving a walkable distance or buying throwaway fashion pieces.

Cook is positively evangelical about the 5:2 theory - but would it work for everyone? The advice seems relevant for and tailored to parents in particular (the author lives in London with her husband and three children), especially when it comes to relationships and screen time; but though that may be her key audience the concept could have a far wider reach. How many of us spend so long worrying about something that we become unhappy and unable to sleep ? When was the last time you did one task at a time, with no distractions of the internet or mobile phones, or said 'no' to something instead of fearing you might miss out? The thought of trying to change those detrimental habits for good is overwhelming, but with the 5:2 process applied, all it takes is baby steps to make a valuable change. Cook emphasises that there is no need to take it all on at once, too - simply pick the area of your life that feels off balance and work your way from there.

Instant improvements for me were the worry sections, whereby I just have to practise mindfulness twice a week for a calmer outlook, and the finance chapter which can slightly blow your mind if you're not very aware of how much you spend without a moment's thought. The idea of ditching the internet and all screens for two nights a week is tempting… in fact, now that I’ve spent one evening finishing off reading the book, I'm already half way there.

5:2 Your Life by Emma Cook is available on  Amazon , £10.99.

Find out more about the  5:2 diet and how it works here , as well as recipes, meal plans and tutorials.