“There is a lot of initial evidence to suggest that temporary periodic fasting can induce long-lasting changes that can be beneficial against ageing and diseases. 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 get close to what fasting does. The beauty of fasting is that it's all co-ordinated”
Dr Valter Longo
I like food. I like choosing fabulous ingredients; I like cooking and experimenting with different recipes, and I like eating. Food and eating are essential parts of our lives and not just for survival – we use food to celebrate, to share, to show care, to have time together and just to enjoy the pleasure of eating really good food. It's not a coincidence that in virtually all cultures, food is central to the important rituals of life and our hunter-gatherer ancestors would have appreciated every meal, especially as they could never be sure when the next one was coming along.
Today, however, we are surrounded by food all day, every day. Adverts tempt us with the latest offerings and every supermarket is packed with snacks, ready meals, tins, jars and packets of just about anything we might want to eat. We can eat pretty much anytime we want to – and we do.
But there is increasing evidence that this constant refuelling is not good for us and that not eating i.e. fasting, has huge benefits for our health and longevity. For hunter-gather communities both ancient and modern, fasting is a way of life – if you can't eat until you have caught or gathered your next meal as opposed to going to the pantry and opening a packet, then there will be periods of time when you simply don't eat - maybe quite long periods of time. And that is how our bodies are designed to work. The latest evidence on fasting is that it stimulates all kinds of beneficial changes in how our bodies function and these in turn can lead to some exceptional health benefits. There are lots of excellent resources on fasting which go into great detail on the science and benefits of fasting and I will list these at the end of the post. But for now, here (briefly) are some of the benefits of fasting:
1. Reduced insulin levels
Insulin is a key hormone which has an important role in balancing our energy and fat storage. However, the modern Western diet is so full of refined carbs and sugar, an increasing number of people are, well, increasing because of excessive insulin stimulation; high levels of insulin cause the body to store fat and can lead to insulin resistance, obesity, chronic inflammation and Metabolic Syndrome. When you fast, insulin levels fall dramatically and this has knock-on positive effects.
2. Fat loss
When you fast, insulin levels fall and your body will move into fat-burning mode. Without a constant supply of food coming in, the body does what it's supposed to do and starts using fat reserves; the reason we store fat in the first place is to ensure that there is energy available even when food is scarce. Fat is drained from the liver and stored fat is released to provide energy. Fasting is a great way to get rid of belly fat which is the most harmful kind.
3. Autophagy
The word autophagy means 'self eat' which sounds seriously gross but it's actually an extremely efficient and neat way for the body to clear out old and damaged cells. When we're stuck in constant refuelling by eating all day, the body knows there's plenty of food so it doesn't need to focus on preservation. Dr Michael Mosley uses the good analogy of having a car, constantly putting fuel in and driving it fast but never stopping to repair and service it. When you fast your body uses the time to repair damaged cells and get rid of old and damaged ones; for this reason, increased autophagy may also help prevent some cancers.
4. Improved immune system
Dr Valter Longo , Director of the University of Southern California's Longevity Institute, found in research studies that intermittent fasting can improve immunity by stimulating the body to switch on stem cells and regenerate the immune system. Our immune systems get weaker as we get older, so finding a way to help strengthen and support it has to be a good thing.
5. Anti-ageing
The modern Western diet and lifestyle causes systemic inflammation in the body. Inflammation is the body's natural response to harmful stimuli such as an injury, a bee sting or a twisted ankle etc; the body responds to protect, repair and isolate the injury and produces inflammation, swelling and pain. But like the 'flight or fight' response I blogged about a few weeks ago, inflammation is meant to be a short-lived, temporary state. A diet filled with sugar, grains and industrially produced vegetable oils coupled with chronic stress and poor exercise habits puts the body into a constant state of systemic inflammation which, over time, is extremely damaging. Heart disease, obesity, cancer, asthma, rheumatoid arthritis, and even dementia have all been linked to systemic inflammation and oxidative damage. Through autophagy, reduced insulin production and cellular repair, fasting can reduce many of the symptoms of ageing and allow us to live longer and healthier lives.
6. Improved gut health
Our guts are teeming with trillions of bacteria which play an important role in digestion, health, weight and even mental well-being. One of the important ones is called Akkermansia. Akkermansia strengthens the gut wall and reduces inflammation. A study in Belgium showed that over-weight mice given Akkermansia had a far-reduced chance of becoming obese and developing diabetes, but the key thing with Akkermansia is that it thrives when your gut is empty so fasting is a great way to encourage this little goody to thrive.
“There is nothing you can do to your body that is as powerful as fasting”
The Fast Diet
A bit of myth-busting
There are a lot of myths about fasting which it would be good to dispel before I go any further:
Fasting will slow my metabolism because I'll go into starvation mode
In fact, the opposite is true – Intermittent fasting actually increases your metabolism. For hunter-gatherers short of food it would have been essential to have the energy to go looking for it, not slowing down.
I´ll be so hungry I'll eat the dog
This is a natural fear but in fact, hunger actually comes in waves rather than building and building until you can't cope. If you can ride the wave by distracting yourself or having a drink of water, the feeling passes quite quickly.
My blood sugar will go low and I'll faint
Unless you're diabetic, your body has perfectly good mechanisms in place to prevent very low blood sugar. If you're used to eating or snacking frequently through the day, especially if you're used to eating quite a lot of carbs, it might be a challenge but apart from feeling a bit grumpy or a bit light-headed the first time you do it, you won't come to any harm. It has also been shown that IF over time actually improves mood and can help with depression.
Won't I lose muscle?
That's the thing with fasting – Intermittent Fasting (IF) has been shown to primarily reduce fat. Because you're not restricting calories every day unlike many diets, you won't lose muscle mass.
But the advice is to eat frequently through the day?
Mmmmm – advice invented and encouraged by snack manufacturers unfortunately. There is absolutely nothing natural about eating constant small meals – it's simply not what our bodies have evolved to do. Part of the problem here is that we have become very dependent on carbohydrate-based food which in turn is a result of the completely discredited low-fat mantra. Eating good quality, low-carb, moderate protein, higher fat food will gradually lessen a desire for snacking.
Who shouldn't fast?
First and foremost, if you have any doubts or are on any medication, it is essential that you consult your doctor before going on a fast.
Fasting is not recommended for:
• People with eating disorders
• Children under 18 years old
• Pregnant or breast-feeding women
• Type-1 diabetics – Type 2 diabetics on medication should definitely consult their doctor
• People who are frail or underweight
• Anyone is is unwell or recovering from surgery
How to do Intermittent Fasting
Ok – so at last the meaty bit (possibly the wrong turn of phrase there).
Fasting can be done in different ways and which one suits you best will depend very much on your own health and circumstances.
Before you start, choose a good time – not when you're stressed or facing other challenges, and definitely not at a time when temptation will be strong, such as a holiday, celebration or Christmas. Give yourself the best chance to succeed. If you can get another family member or friend to join you, it always helps.
It is also essential to make sure that you are getting the right nutrition – there's a world of difference between 500 calories of good nutritional food and 500 calories of ice cream and chips.
5:2 fasting
The method tried, tested and promoted by Dr Michael Mosley, it is the one most people know and that has had phenomenal success for many people. The premise is simple – eat normally (with an eye to a reasonably healthy diet) for 5 days a week then fast for 2. In this case, fasting isn't even going without food completely, but just reducing your calories to about ¼ on fast days; for women this is around 500 calories. The real benefit comes from going as long as you can without eating as this is where the positive effects listed above start to kick in. When I have done this, having my 500 calories all in one go for dinner works best because I find that if I eat anything in the day, it just triggers hunger and it's much more difficult, but many people, including Dr Mosley himself, prefer to split the calories over two meals – breakfast then nothing until dinner. You will need to try it and see what works best for you. The important thing is to make those calories count – a good protein, lots of low-carb veggies and a small amount of good fat will keep you properly nourished and feeling full. Really try to avoid the starchy carbs as they will just trigger an insulin response which will make you very hungry. It's also best to avoid alcohol on fast days as most alcoholic drinks are high in calories and alcohol will make you peckish.
The reason so many people find this effective and easy, is that they know if they're craving something 'naughty', they can have it tomorrow; surprisingly though, many people find they don't want to binge the next day.
The days you choose don't matter, just as long as they fit in with your life, although regular days will help keep you on track. Mondays and Thursdays work for me but you need to find what works for you. Some people even do their fast days back-to-back to get them done, but this is obviously more challenging.
Alternate Day Fasting (ADF)
This is a more dramatic version of the 5:2 where you fast every other day. It can be extremely effective if you want quick results but it is challenging, not least because it's so hard to plan anything. Dr Krista Varady of the University of Illinois studied the effects of ADF with human volunteers who were asked to eat all of their calories (500 for women) in just one lunchtime meal. She found that even if the volunteers ate junk on their feed days, the positive effects were still as strong. Two things are thought to contribute to this – firstly, people are more likely to comply if there are absolutely no rules on the feed days; secondly, it's almost impossible to overeat on the alternate days – most volunteers only ate 110% of their normal calories even with no restrictions. You could also try 4:3 (4 days eating normally and 3 days fasting) which is similar but not as hard to plan.
I think this is something worth trying once you've got the hang of 5:2 or if you really want a kickstart, otherwise it might be just too hard.
Time Restricted Eating (TRE)
This is a way of fasting that has been shown to give good results. As the name implies, calories aren't restricted but the time in which you eat is. Basically, each day, you eat all of your calories in a time frame of about 8 hours, so, for example, lunch at 12.00 and dinner at 8.00. This gives your body a good 16 hours of not eating which has been shown to be very effective. One way to get into this is just to extend the time before you eat in the morning as long as you can. So for example, if you normally eat breakfast at 8.00, try to extend it until 9.00 or 10.00, then gradually increase the time.
There's no reason why you can't combine TRE with other methods of fasting if you want to.
Full Water-only Fast
This is an extreme version of fasting which involves having no calories at all for 24-48 hours. It's actually a good demonstration of how hunger doesn't just keep building. In fact, when I have tried this, I find that the hunger actually disappears after about 24 hours. Dr Valter Longo recommends a 4 day full fast every few months to achieve outstanding benefits but this really needs to be done under medical supervision. A 24 – 48 fast is an interesting experiment for anyone wanting to try out a full fast.
Resources
There is so much information out there, especially in cyber-world, that it can be very confusing. So much of the information is contradictory and some is actually false and potentially dangerous. I joined recently (and unjoined very quickly) a Facebook group on fasting where one poor lady was told that because she had eaten a small handful of micro-leaves, she had wrecked the fast and had to start again! You just don't need those kind of food police.
The books and resources I list here are ones that I have found informative, useful and trustworthy. And just for the record, these are absolutely my own recommendations – I don't receive any payment or reward for listing them.
Books
The Fast Diet – Dr Michael Mosley. The Fast Diet UK website is also a good source of support and information.
The Fast-800 – Dr Michael Mosley
The Obesity Code – Dr Jason Fung
The Longevity Diet – Dr Valter Longo
The Fast Diet Recipe Book – Dr Mosley and Mimi Spencer – This is great for fast day recipes and advice
The Blood Sugar Diet Recipe Book – Dr Clare Bailey and Dr Sarah Schenker – not specifically on fasting but as the Blood Sugar Diet is essentially low-carb and low-calorie, the recipes are very useful.
Documentaries
Eat, Fast, Live Longer – Horizon documentary with Dr Michael Mosley. Available on the BBC or on Daily Motion if you're outside the UK
I would love to hear about your experiences with fasting so please leave comments, questions or ideas on the website or Facebook page.
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