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Wednesday 11 July 2018 1:50 pm  |  Updated:  Thursday 22 August 2019 1:56 pm

The fast and the curious: Answers to all your questions about short term fasting for health

By: Harry Thomas

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Last week I wrote about completing a three day water fast, during which I ate and drank nothing but… water. Since then I’ve received messages from people all over the world wanting to know more. Here are some answers to the most frequently asked questions.

Is it dangerous?

Despite fasting having been around for thousands of years, I got a lot of messages from people who were astonished – and occasionally horrified – that someone can go for three days without eating (people can, in fact, go for three weeks without eating, so it isn’t all that extreme). I must admit, though, that I did feel like I’d achieved something, and since that article people have been inspired to try their own fast. 

A common question was whether fasting is in some way dangerous or unhealthy. For anyone considering it, my advice is always to start small, be mindful of how you feel and, if you’re in any doubt, think about consulting your GP (especially if you have a pre-existing medical condition). But is fasting inherently dangerous? No.

But neither do I think it’s a long-term weight-loss solution, or that it will be a good fit for everyone. You need to be careful with your body, and if you’re doing something like fasting that will shock it, you should make sure you have access to people who can help if you start to feel unwell. You should also make sure you’re doing it for the right reasons – short-term fasting should never turn into long periods of starvation. But at no point did I feel at risk or “unhealthy” – I felt great.

What can you learn?

People I’ve spoken to about fasting say they have learned a lot about themselves. People realised their willpower was stronger than they believed, or noticed how much they depended on things like fizzy drinks. They realised they didn’t need to eat something – at a work do, for example – just because there’s food on the table. They learnt to say no.  

One client realised there’s no need to completely revolutionise his diet at this point in his life, but discovered he could quite easily eat less throughout the day.  Other people noticed improvements in their skin, had better bowel movements, and found it easier to concentrate in long meetings.

I also know a few people who absolutely hated the experience. One of my friends had a headache and a bloated stomach for three solid days. He was miserable. A few felt fatigued and lacked energy to train. Others found it difficult to complete the fast, in part due to their social and work lives, and decided to end it early. There are no right or wrong ways to feel about this.

How did you feel afterwards?

Since completing my fast, I’ve been monitoring a number of things in my life to see if it really did have a positive effect. In terms of mood, I’ve felt great – upbeat and energetic. The fast might not be the only reason, but it’s certainly a contributing factor. I’ve been more productive, too. We’re currently opening a new studio at No1 Fitness, and for those of you who have dealt with builders, you’ll know how much it can take out of you.  So my days are busier than normal, but I’m getting more done.

I’ve been monitoring my sleep using the polar watch, and its quality has improved. I’m sleeping for longer, but I am also averaging an extra 45 minutes of deeper, uninterrupted sleep. When I wake early in the mornings, I feel alert rather than groggy (another thing I’ve noticed is that my dreams have been especially vivid). 

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Harry after three days of water fasting

Perhaps most importantly, though, I notice so many more things about my eating habits. Even personal trainers tend to live on autopilot when it comes to food and drink. Since fasting, I pay more attention to what and when I’m eating. I’ll notice that I’m instinctively drifting towards a pastry in a coffee shop and ask myself if I’m actually hungry – quite often, I’m not.

After dinner, I always used to crave food. Fasting gave me the tools to fight these cravings. Most of us eat habitually rather than out of pure hunger, which can easily lead to over-eating.  When you pay attention, you can make small changes that have a positive effect on your life.

Is it a good way to lose weight?

During the fast I lost 3.2kg (6lbs) in just three days. A lot of this could have been water, and many people have told me I was bound to put it all straight back on again. In the three weeks since, I’ve put on 0.5kg. 

I think people are confusing fasting with “crash dieting”, which often means starving yourself and subsequently bingeing. This, of course, can lead to people putting on more weight than they lost in the first place.  The key is being aware of the food you re-introduce after the fast. If you plan the number of calories you consume, you can quite easily sustain weight loss.  

Should I do it?

If you’re considering a fast, pick three days in your diary when you don’t have much on. Don’t tag along to restaurants and bars – it’s not fun watching people eat while you fight waves of hunger. 

Train while fasting, even if you think you have no energy – you’ll get through it and feel so much better afterwards. 

Lastly, try to enjoy it – this is about feeling good, after-all.

• Harry Thomas is a personal trainer and co-owner of No.1 Fitness. Go to no1fitness.co.uk or call 0207 621 1312

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