Definitely not another crazy diet fad – intermittent fasting (IF) is based on an ancient practice that has been embraced since the dawn of time in most areas of the globe and across many faiths. The revival of IF is thanks to promising studies and recent research that prove the benefits which range from reducing the effects of ageing, preventing serious health issues, while simultaneously allowing the body to repair and protect itself, like minimising obesity, high blood pressure, asthma and overall inflammation among others (1). The 5:2 Fast Diet as coined by the incredible Dr. Michael Mosley and Mimi Spencer in the bestselling book, ‘The Fast Diet’, gives us the practical application for adopting this lifestyle that we know really works from anecdotal evidence (2).

how quickly does the 5 2 diet work

How to do the 5:2 diet plan

The plan overturns our current bad habits of eating too much, too often, which is a big contributing factor to many of our modern diseases. Essentially, it’s about increasing the space between our last meal and the first meal to ‘break the fast’ the following day, which, when done regularly provides all these health benefits. For example, if you ate dinner at 8pm on Tuesday night, it's said you should leave a window of 14 hours before eating again, so waiting until at least 10am on Wednesday morning. 

The 5:2 plan goes one step further where you restrict calories to 500 calories for women and 600 calories for men, two days a week and follow a loosely Mediterranean diet the other five days. This reaps the most health benefits other than boosting metabolism and weight loss and is easy to put into practice once you get used to it because it’s flexible and you don’t feel desperate and deprived like you’re ‘on a diet’. You can still enjoy most of your favourite foods, for most of the time – two days a week isn’t that big a deal, I promise. As you become more conscious of the impact that what you eat has on your body, you might find yourself craving a pizza a whole lot less... and just knowing you can have it tomorrow really helps!

long term effects of 5 2 diet

Does the 5:2 diet work for everyone?

Put simply, going without food for short periods of time a few times a week mimics the way we were evolved to eat when feast and famine were all we knew – when our bodies are exposed to stresses and shocks it performs better. As Dr. Mosley states, "Intermittent fasting allows our bodies to do lots of the other functions it can’t carry out when it spends most of its energy and resources on processing and digesting food. (2)"

So things like cell regeneration and gene repair are switched on, says Professor Valter Longo, Director of the University of Southern California’s Longevity Institute who has studied fasting for many years and concludes that, "You take a person, you fast them, after 24 hours everything is revolutionised. And even if you took a cocktail of drugs, very potent drugs you will never even get close to what fasting does. (1)"

Intermittent fasting takes away the pain and deprivation of constant calorie restriction but still provides the same benefits to our bodies.

Dr. Michael Mosley himself easily lost nearly 20lb (8kg) and improved his cholesterol levels and dangerously rising blood glucose levels, so reversing the impending type 2 diabetes he was facing (2). 

Personally, I see the health benefits because it means we eat more gut healthy veggies like broccoli, cauliflower and leafy greens. We know that eating more like ten portions of veg with a little fruit, is the easiest way to boost our energy levels. This is always the first and foremost advice I give to most of my clients who want sustained health improvements. Green veggies offer more nutrition per calorie than any other food out there, so there’s no reason why you should feel deprived on fast days with so many beautiful rainbow veggies on offer (3). 

With just 25 calories per 100g, cauliflower is my go to on fast days and I have built lots of delicious low-calorie recipes around this little superhero along with other low-calorie stars like courgettes, mushrooms and gorgeous seasonal veggies such as asparagus, brussel sprouts, purple cabbage and beautiful berries.

We have created our own take on the low cal diet which will be a feast for your eyes and your belly and you won’t feel hungry or tired or even notice you’re ‘fasting’. If you want to find out more about the SJ Health 28 day fast diet programme we’re running all January, please visit for lots of recipes, top tips and support.

Please note: Fasting is not for everyone – this is not for children and you should never fast while pregnant, breastfeeding or if you have certain other health conditions. Always speak to your health practitioner before embarking on a new eating plan.

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Want the best way to focus your mind, boost your mood while losing weight for 2018? Look no further than intermittent fasting for long-term proven results.


1. Longo, Valter D and Mattson, Mark. ‘Fasting: Molecular mechanisms and clinical applications’.  Cell Metabolism, 19 (2), February 2014.
2. MOSLEY, M, SPENCER, M. 2014. ‘The Fast Diet’.  London. Short Books.
3. Aune D, Giovannucci E, Boffetta P, et al. Fruit and vegetable intake and the risk of cardiovascular disease, total cancer
and all-cause mortality–a systematic review and dose-response meta-analysis of prospective studies. International Journal of Epidemiology. Published online February 22 2017.

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