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What about fasting?


Advent is nearly upon us – and it may surprise you to hear that Advent was once a season of fasting! It was a way of preparing for Christmas, rather like Lent. Then it fell from favour, and fasting was seen as an unusual religious practice: something that only ultra-dedicated people did.

But after the Horizon TV documentary Eat, Fast and Live Longer appeared four years ago, fasting (or ‘reduced calorie intake’) entered popular news headlines. All sorts of claims were made for fasting: improved memory, reduced risk of cancer and diabetes, a longer span of health and even a longer life.

Hardly surprising, then, that many clients ask me about fasting, and whether it could be useful for them. So our questions for this blog are: is fasting worth it – or is it just a fad? Could it really be physically healthy?

Part of our difficulty with fasting, is that it’s unfamiliar. We’ve largely forgotten our histories of calorie restriction in the West. In England, fasting was once a part of public life. Until the seventeenth century, most of society followed the Christian church’s calendar of fasting and feasting. Fridays were Fast Days, and Sundays were Feast Days, when poorer families might eat meat for the only day in the week. During Advent and Lent, people would abstain longer from rich foods such as meat, eggs, butter and milk (chocolate bars hadn’t been invented yet!). This is why people traditionally used up their eggs, milk and butter, to make pancakes on the day before Lent started. And even now, regardless of what we believe, many of us give up foods we like for Lent.

So, perhaps fasting isn’t quite the fad it might seem. Let’s now have a look at the different types of fasting one can undertake. First of all, there is total abstention: no food or water. Humans can’t live for much longer than three days like this, and for most people it’s definitely not a good idea to go without water.

Abstaining from food alone can be done for longer; the maximum is about a month or so. Anything longer than a day, however, should only be done under consultation with a health professional who can assess your suitability.

Other types of fasting include: intentionally missing a meal, fasting food for a day, or fasting certain foods for a period of time. One way of undertaking a prolonged fast (say for a week or so) is to eat only vegetables and drink only water. But again, it is always worth checking with your doctor first whether this is sensible. A sudden lack of protein can be a bit of a shock to the system, as of course can a lack of food generally.

The recently-publicised 5:2 diet suggests you eat whatever you like for five days a week, and then only 500 to 600 calories per day for the other two days. In food terms, 600 calories would be one piece of ham, two scrambled eggs, one portion of fish and some vegetables, and just water to drink.

But how might fasting benefit our bodies? Michael Moseley made several claims for it – and particularly 5:2 fasting – in his Horizon documentary, but was it corroborated by science? The NHS website assessed the claims in 2013 and acknowledged studies made in 2010 and 2012, that 5:2 or ‘intermittent’ fasting might well decrease weight, risks of diabetes, and cancer.

Scientific research in the last couple of years also seems to corroborate the potential physical benefits of intermittent fasting. In 2014, one report suggested it could decrease inflammation and protect the brain; in 2015, a study on mice suggested that fasting may rejuvenate the immune system, reduce the risk of cancer and improve brain function, concluding that in humans it would reduce the risk of age-related diseases. This year, another animal study found that intermittent fasting reduced inflammation and autoimmunity generally, as well as the symptoms of MS in particular. While animal studies aren’t as reliable as human ones (and human studies are always rarer when new ideas are being tested out), they do offer some positive evidence to support the anecdotal human successes of the media headlines.

Why would fasting work like this? It would take a whole extra blog to deal with this properly, but perhaps the simple answer is that fasting gives the body a break from the hard work of digestion. During the normal processes of breaking down even healthy foods, our own bodies produce some of the most toxic substances we encounter. Fasting also gives the body a chance to focus more on repairing itself. A time for doing some housekeeping!

Other reasons to fast might be to express solidarity with those who do not have enough to eat, to set aside time to pray, to increase a sense of gratitude for the food you have, or to donate what you would have spent on food to people in need.

One final example from my own practice is a client who found herself addicted to eating chocolate every day. Moderation just wasn’t working! So I suggested she avoid it completely as a fast for 40 days. As it turned out, she found it easier to abstain from it altogether, than to eat it occasionally or in small amounts. She also discovered that she wasn’t as reliant on it as she believed she was – she could even enjoy life without it. You might be an all-or-nothing person too, and find that fasting a ‘problem’ food item for 40 days helps you gain control over a stubborn habit. Or you might perhaps experiment with fasting in Advent.

At this point, you may be asking yourself whether you would do well to fast or not. Before you decide, I would say once again – it is always wise to consult your health professional, particularly if you have any known health issue. Don’t restrict any food or food group for longer than a day without taking advice.

Another issue would be any psychological/emotional challenges connect with food. I would certainly advise the strongest caution to anyone who has, or has ever had, an eating disorder. And for anybody, it is always worth letting a reliable person know if ever you decide to fast, so that they can support you.

After all, any new adventure is best undertaken in wise company.

Have you had any experiences of fasting? I would love to hear them.  Or are you thinking of trying it? Feel free to be in touch and I would be happy to offer any support and advice I can.

With best wishes for a happy, healthy season ahead,


Emma Maitland-Carew, Nutritional Therapist in Oxford and Bloxham, Oxfordshire


Brandhorst, S. et al., 2015. A Periodic Diet that Mimics Fasting Promotes Multi-System Regeneration, Enhanced Cognitive Performance, and Healthspan. Cell Metabolism, 22(1), pp.86–99.

Choi, I.Y. et al., 2016. A Diet Mimicking Fasting Promotes Regeneration and Reduces Autoimmunity and Multiple Sclerosis Symptoms. Cell Reports, 15(10), pp.2136–2146.

Fann, D.Y.-W. et al., 2014. Intermittent fasting attenuates inflammasome activity in ischemic stroke. Experimental Neurology, 257, pp.114–119.

Grumett, D. & Muers, R., 2010. Theology on the Menu: Asceticism, Meat and Christian Diet, London ; New York: Routledge.

Harvie, M. & Howell, A., 2012. Energy restriction and the prevention of breast cancer. Proceedings of the Nutrition Society, 71(2), pp.263–275.

Harvie, M.N. et al., 2011. The effects of intermittent or continuous energy restriction on weight loss and metabolic disease risk markers: a randomised trial in young overweight women. International journal of obesity (2005), 35(5), pp.714–727.

Mosley, M. & Spencer, M., 2016. Welcome to 5:2 intermittent fasting » The Fast Diet. The Fast Diet. Available at:

NHS UK, 2013. News analysis: Does the 5:2 fast diet work? – Health News – NHS Choices. Available at:

Wirzba, N., 2011. Food and Faith: A Theology of Eating, New York: Cambridge University Press.

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