Fast & Curious: The Benefits of Fasting for Mind and Body

Does fasting have a positive effect on your health and wellbeing? Beauty expert Katy Young explores the benefits of giving our digestion a much-needed break

Any stalwart of intermittent fasting will tell you that limiting the hours you eat food is a perfectly familiar practice that dates back centuries to our days as hunter gatherers. They will go on to tell you this is exactly why we would do so well to relive the ancient habit. What they might not tell you, is that cavemen didn’t choose to fast. In fact they were inadvertently starving between hunts, paving the biological way for later generations living through feast-or-famine epochs who were then protected by our innate ability to fast. Roll on a few thousand years, and we’re choosing to return to the idea of cutting down on meal times – but do our 21st century guts really want us to?

Well, put simply, yes. While you might expect 120,000 years to witness a sea change in the way we eat, it does comparatively little to the evolution of our guts, which take far longer to advance than, say, our brains, bones and muscles. Add in today’s menu and you have a perfect recipe for modern-day disease, including diabetes, fatigue, IBS and obesity, all associated with a gut quite literally sick of too much 21st century processed food. No wonder exercising a little bit of restraint and returning to slowed ways of eating feels so appealing.

Most of us will sign up the practice of fasting for its physical benefits, of which there are many. Our interest is often piqued for the fat loss associated with it, which pleasingly comes without the muscle loss usually associated with crash diets that shave off the inches. This is all thanks to the release of certain hormones, including adrenalin and epinephrine, which trigger your body to tap into fat reserves while simultaneously preserving and encouraging muscle mass, density and tone.

But this is not the only physical benefit, far from it. When we fast for over 10-12 hours, we automatically switch our source of energy from glucose in the liver to ketone stores in fat, which trigger major effects on the cells and organ function. Our cardiovascular health loves it, which is why you might notice your skin, hair and nails looking healthier as our nutrient update improves. What you might not be able to see, but will almost certainly feel, is a decrease in blood sugar and blood pressure, oxidative stress and cholesterol. And then there is the well documented science of cell regeneration, which occurs as fasting trips our system into autophagy, whereby old cells are eaten up by newer, more efficient cells in a kind of ‘cell clean-up’ of the entire body.

Neuroscientists have also long studied the happy cerebral side effects of fasting.  The theory goes that wild animals are hardwired to perform better during periods without food so that they are better placed to catch the prey that they so desperately need after a couple of weeks of nothing. Similarly, in lab trials, studies with animals found that when running off stored fats rather than glucose, as we do during bouts of no food, the brain and body perform better, with improved cognitive function, learning, memory, alertness and stress resistance. This of course makes for a far better hunter in the wild, and in our case, say scientists, a much higher performing human in today’s society. Fasting essentially puts the brain into survival mode, and activates a hyper focussed state so that we are essentially preserving energy for whatever the task at hand is. In a world associated with low attention span and endless distractions, such true focus in hard to find.

But while there might be a sense of empowerment in fasting, there is no need for the obsession often associated with dieting, whereby counting calories, macros or portions can feel like a full-time job. (Worryingly, studies have linked this kind of mania over what we are eating with disordered thinking around our food, as well as anxiety, guilt and even orthorexia). Simply put, fasting is not really a ‘diet’ at all, but mealtime-planning. It comes down to not what you eat, but when you eat. Once you have chosen which 24 eating clock to live by – whether it’s skipping meals, fasting for a full 24 hours, intermittent fasting and daily window fasting, there is real freedom of choice.

So what plan to choose? The general consensus for newcomers is to start off with a 12-14 hour fasting window, working your way up to a 16-hour period for better health benefits still. And beginners take note that while both sexes can fast to similar effects, women tend to find the practice harder, thanks to a reproductive system which signals hunger more aggressively. Though please do not undertake any drastic changes to your food intake without consulting a doctor or nutritionist first.

While fasting isn’t for everyone, your gut will find it hard to deny the benefits. As the old adage goes, don’t dig your own grave with your knife and fork. Instead, we suggest, putting them down entirely between restricted meal times for a better quality of life.   

Which fasting type is right for you?

‘There are lots of different variations to intermittent fasting,’ says nutritionist Jennifer McDiarmid. ‘The key is to pick one that you can achieve with relative ease. Think about how your normal routine runs: when you wake, when you go to bed, how your mornings tend to go, and so on. Be realistic about what will work for you. Set yourself up to succeed, not fail!’

5:2 Method

Traditionally people use the 5:2 method. This method is where you only eat 800 calories for two days a week and the other five days a week you follow a balanced eating approach.

Recent advice suggests that on the non-fasting days you try and follow the principles of Mediterranean eating consuming whole grains, fruits, vegetables, beans, herbs, spices, nuts like pistachios, and healthy fats such as olive oil.

12:12 / 16:8

More recently, intermittent fasting has changed, and people are now choosing to do the 12:12 diet where you fast for 12 hours a day, which includes the time you sleep, or the 16:8 where you fast for a 16-hour window – again this can include sleeping time. ‘This can be easier for people, as during the eating periods, you aren’t needing to calculate calories and can eat when hungry,’ says Jennifer. It is also likely that either of these methods will fit into the natural rhythm of your day, making it a small, manageable lifestyle change. And not a dramatic overhaul. Remember, during the eating window, it’s important you try to keep to balanced eating.


This stands for ‘one meal a day’. It is an incredibly extreme version of intermittent fasting – and something that is more linked with religious fastings, such as Ramadan. It is not to be recommended without guidance from a nutritionist or doctor.

‘Choose whichever version suits your needs,’ says Jennifer. ‘Remember to make sure you are not just focusing on the time or calories you are eating, but to make sure you are getting as many nutrients as you can to avoid nutrient deficiency, which can occur when we start to embark on any form of restricted eating.’

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