My Five Day Water Fast

If you've just raised your eyebrows at my five day fast and have a comment to poke fun at my most recent experiment, then you're not alone! I received a whole lot of those this week so before I get into all the detail, here are my best rebuttals when I told people I was only going to drink water for five days:

  • Them: OMG, won't you die of starvation? Me: 1. If humans died after a few days of not eating, I don't think the human race would have survived as long as it has, do you? We are in unprecedented times with food on tap 24/7. We didn't always eat breakfast, lunch, dinner, snacks, midnight feasts etc etc you know, and sadly we are now a chronically sick and unhealthy generation. Go figure.... And 2. starvation is a situation outside of your control, fasting is optional and I'm lucky enough to be able to eat if I want to, there's a huge difference.
  • Them: I could never do that! Me: It's more mind over matter, if you understand how beneficial it can be (see below for details), you are intent and committed to trying it for yourself, and you've dabbled in fasting before, it's actually not too bad.
  • Them: I don't think that's good for you Me: It depends on your current state of health, there are some caveats for different people, e.g. those with hormonal or blood sugar issues; women should consider potential impacts on hormonal health and insulin dependent diabetics should be under doctor's supervision. But there are different methods to try fasting (see below for details).
  • Them: Seriously? ONLY water?! What kind of water? Me: good quality filtered water with added sea salt and/or trace minerals (see below for details). After day three I did enjoy a cup of black coffee and some peppermint tea because neither of which contain any calories, which can kick-start your metabolism
  • Them: I go to the gym to build muscle so I can't fast or I'll lose it. Me: If you look at the science and physiology behind fasting (and try it for yourself) I think you'll find that the body is very clever and uses fasting a bit like pruning a tree to make it grow stronger and bigger again. The body doesn't break down muscle proteins, once it's burnt through your glucose stores it sticks to burning fat and has a pretty unlimited supply of calories from that.

I must also say that if you are considering trying fasting you should always check with your Doctor first, but it will help to do some research for your own sake and then you can present them with some studies to highlight the benefits! Some of what I write below is my own personal experience, it's highly likely yours will be different so be sensible and listen to your body.

NB You should not fast if you are pregnant or breastfeeding, a child, underweight, malnourished or on certain medications, for example, insulin or warfarin (check with your doctor), or if you suffer from gout. 

This blog is quite long but if you're interested in trying fasting, you'll want to know, so read on!

Why Fast?

Personally I wanted something to kick-start a reset after the heavy and intense Christmas/New Year period, plus I wanted to experience both ketogenesis and fasting as they are tools I can recommend to clients and I need to know what I'm talking about!

Whilst fasting has been practiced in many populations and religions from Ancient Greece (for cognitive improvement - maybe that's why they were such great thinkers!) to native Americans, to Ramadan and Lent, studies of its effects on the body are only just starting to come through. In primitive cultures, a fast was often demanded before going to war, or as part of a coming-of-age ritual. The use of fasting for health and healing was document in the early 1900s when it became popular as part of the Natural Hygiene Movement in the US and Nature Cure in the UK, and since then it has also been used as a means to protest, most famously by the Suffragettes and Ghandi whose longest fast was 21 days!

The anecdotal accounts of the history of fasting (excluding the extremists who took it to detrimental lengths ultimately leading to their demise!) are mostly positive. With the modern studies being carried, for example by Profesor Valter Longo, a scientist hailed as one of the most influential people in health in 2018, we are now getting specific data for when fasting can be most beneficial. Dr Longo's work shows how even a fasting mimicking diet (FMD) can enhance, and aid in the treatment of, certain types of cancers, neurodegenerative diseases, autoimmune conditions, cardiovascular diseases, diabetes and obesity. For a deep dive into the science of Dr Longo's work listen to this podcast with him and the amazing Dr Rhonda Patrick.

Dr Jason Fung is also a world-leading expert on intermittent fasting and low carb who has had extensive success with his Intensive Diet Management program particularly for the treatment of type 2 diabetes. For a brilliant run down on Fasting from Dr Fung listen to this podcast with him and one of my favourite health gurus Ben Greenfield. You'll also find a brilliant summary with loads of science in this Complete Guide to Fasting article by Dr Mercola where he discusses the practice with Dr Fung.

From some of the research and studies, I've listed a summary of some of the benefits of fasting (as you can see there are many!):

  • getting your blood sugar back under control by restoring sensitivity to insulin (see study). This is huge and is why fasting is used to help treat diabetics (under Dr's supervision). Human Growth Hormone (HGH) is suppressed by insulin so a better sensitivity is beneficial for many reasons.
  • helps to reduce inflammation and 'refresh' your immune system (see study
  • improved blood pressure, triglycerides and cholesterol levels (see study) to lower the risk of heart disease
  • a boost of brain function and prevention of neurodegenerative disorders (studies are mainly in mice, need more evidence for humans, but anecdotal evidence and use of the ketogenic diet report improved cognition)
  • weight loss!! Theoretically removing or restricting caloric intake will promote fat-burning and weight loss. This was the most noticeable physical benefit for me. I didn't weigh myself because I don't find this a true measure of anything really, but I felt better, lighter and have noticeably dropped inches from places! At a guess I would estimate 4kgs, but that is likely just what I put on over Christmas haha.
  • boosting metabolism and even muscle strength through the increase of Human Growth Hormone (HGH) (see study). This may seem counter-intuitive, but reducing insulin sufficiently to access fat stores will actually activate your metabolism (if you're a hunter-gatherer you will need this to give you the energy to find food!), clear out the old/worn proteins and rebuild new ones!
  • extend longevity i.e. help you live a longer, healthier life! This seems reasonable since fasting allows your body to clear out the old, to make way for the new. The key repair process here is called 'autophagy' which is when cells cleanse themselves by removing old and damaged proteins, replacing them with new ones and optimizing their function. This will ultimately give your body a better chance at staying free from disease (need more time to allow the human studies to show this, see article). The opposite of a diet high in sugar which accelerates aging.
  • increase the effectiveness of chemotherapy for cancer treatment, a field studied extensively by Dr Valter Longo as mentioned above
  • protect the gut against the negative impacts of stress and can boost your gut flora (see study), making your gut and immune system stronger. 
  • improve your energy levels. You may or may not be surprised to learn that when we are more active when we're hungry and less when we're fed, probably to give us the incentive to go and find our next meal. (See article).

Negative Side Effects?

As long as you are sensible and understand what your body needs and you don't overdo it, undesirable effects should be minimal, and you should see only benefits. I'll tell you some of the things I noticed below but please pay attention to some of the caveats for women. Due to our complicated hormonal connections, and a very sensible inbuilt mechanism to prevent reproduction during times of famine (logical right?), fasting can interfere with our hormones. Hormones are all interconnected in this amazing, complex system, so a change in one can throw the whole system out, therefore fasting for women could potentially result in effects like sleep disruption, irregular periods, anxiety/depression and fertility issues. Women may find that shorter Intermittent Fasting (see below) for 12-16 hours a day is a better option.

These are the three main side effects I personally noticed but you may of course experience others:

  • I did not have any headaches during the first few days which may be common if your body has to withdraw from coffee or carbs (see below for how I prepared for the 5 day fast), and only occasionally noticed slight dizziness upon standing up too fast, which I quickly remedied by drinking more water with salt/trace minerals in it. Salt and trace minerals (particularly magnesium) are important to ensure you prevent dehydration and muscle cramping.
  • One of the things I've noticed even during my regular days of Intermittent Fasting (see below) is that I feel cold a lot of the time with the worst being lack of circulation to my fingers and toes. This could be due to a number of reasons: down-regulation of the thyroid (your body's thermostat), the fact that your body generates heat when metabolising food, or that your body senses the change and prioritises heat to your vital organs and not your extremities. Do what you can to keep warm, I wore socks to bed and gloves when out, sauna and light exercise will also help.
  • Often people experience constipation during a fast, which can be due to the fact you're putting nothing in so there's nothing much to come out, but also because you have no fibre to help your stool on it's way and also because you may be lacking in key minerals like magnesium which help the process along. If you're interested, then this is what happened to me: days one and two no bowel movement, but at the end of day two I had the luxury of an hour long session in an infra-red sauna. This is brilliant for getting deep into tissue and mobilising some of the undesirables that lurk there to help clear inflammation and toxins. I found that not long after this session I got diarrhoea! But it was this weird, darker, different smelling stuff than had I had a tummy bug or something, so there was definitely something extraordinary going on! I'll just say it was a purge of old, unwanted 'sludge' that needed to go and enjoy the cleansing nature of it! Ha.

My Five Day Fast (non-caloric liquid fast)


I read that being in ketosis prior to the fast will make it easier. Ketosis is the state your body is in when it has switched its main fuel/energy source from carbohydrates to fat and this fat burning can actually be measured by the production of ketones as the body breaks down fatty acids. It can take anywhere from a few days to a few weeks to get into ketosis if your diet is low enough in carbs (around the 15-25g/day mark if you're counting Net Carbs = Total Carbs - Fibre), low in protein (as this can turn to glucose if overdone: ~0.8 g protein per kilogram of body weight per day) and high in healthy fats e.g. 100-120g per day), and then up to a year or more to become fully adapted so that you can even perform athletically to a high level in that state. Read more about a keto diet here.

The Ketogenic Diet

The Ketogenic Diet

I started to move to a ketogenic diet on New Year's Day and continued for a week prior to my fast and whilst I made a few mistakes as it was my first time, on the whole I felt better (probably also due to no alcohol after overdoing it at Christmas ;-). Whilst it likely takes two weeks to achieve proper ketosis, even with one week of making mistakes I do believe this made it an easier transition as well as the fact that I normally practice Intermittent Fasting (see summary graphic below) on a daily basis so my body is used to not eating until after midday.

You can count the time you are sleeping in your fast so it's best to start after dinner one night, so by morning you've pretty much done 12 hours already! 

During the Fast:

The key to completing a prolonged water fast (otherwise known as Non-Caloric Liquid Fast  or NCLF) is to ensure you avoid an electrolyte imbalance by adding 1/2 - 1 teaspoon of good quality sea salt to your water and/or use trace minerals (like these). You'll know you haven't quite got the balance right if you feel really dizzy, weak and lethargic, so just take another drink of your salted water. 

On this kind of fast you can consume other liquids as long as they have no calories so this rules out 'bulletproof' coffee (with added fats) because calories break a fast, but allows for black coffee and herbal teas which can also act as appetite suppressants so provide some relief from the hunger! This study shows that coffee (caffeinated or non-caffeinated) promotes the process of autophagy, and another 2017 study shows that it up-regulates ketosis in humans, which is good news for coffee lovers like me. Plus the warm liquid helped with the feeling of cold I mentioned above! Of course if you're looking for the most traditional fast with zero enzymatic activity, water with salt only is the way to go which is Dr Satchin Panda's tendency although there seems to be a lot of discussion on this topic!

As I mentioned above I used infra-red sauna to help detox some of the toxins my fat may have stored and were being released in ketosis. With regards to exercise, I walked for 15-30 minutes outside most days, I also did gentle pilates and yoga classes, but on day four I had a game of squash booked so I warned my opponent and gave it a go without any expectations. Funnily enough I played really well (I haven't played for over a year!) though I did feel a little weak though not dangerously so, I stopped for water every 5 minutes or so and drank plenty afterwards with added salt.

For additional detoxing encouragement I had an epsom salt bath midweek to help me relax and to utilise the magnesium I could absorb through my skin. I did my usual daily dry body-brushing before a shower, alternating hot-cold showers every morning to stimulate my lymph to move (that's the stuff that carries the toxins and other bi-products from your immune system out of the body) and on the morning of day 5 did my usual weekly water and coffee enemas for the final clear-out!! Honestly.....I felt like a million dollars on day 5. I think it was the euphoria of achieving the 5 days, the boost from the coffee and knowing I could eat soon!

Breaking My Fast

Given some of the rewards you can reap from a fast, such as a boost to Human Growth Hormone (HGH) to start the rebuild of fresh proteins in tissue and muscle, it is important what you break a fast with. This is especially if you have completed an extended fast as your stomach may go into shock if you overload it with difficult to digest foods and cause you some gut problems. Having said that, in the podcast with Dr Rhonda Patrick and Dr Valter Longo mentioned above, Insulin Growth Factor or IgF-1 (another proactive signalling molecule) seems to be reactivated by carbohydrates so including a moderate amount of these at this time can be beneficial.

I broke my NCLF after five days with:

  • a warm mug of beautiful homemade beef bone broth with some miso paste, turmeric and lemon juice mid-morning, followed by 
  • a 'bulletproof' style coffee (with butter and MCT oil). 
  • before eating any proper food I juiced up some celery, ginger and lemon to boost my electrolytes again naturally, but this drink contains some calories so I couldn't have really used it on the NCLF,
  • I ate my first actual food around 3pm with some homemade sauerkraut to add some good bacteria, followed by
  • two fried eggs and half an avocado.
  • For dinner I had some celeriac soup with crispy kale chips, it was heaven but I couldn't manage the whole bowl!

I did take some amino acids prior to the bone broth to help rebuild the proteins, these can also be utilised during the fast if you are an athlete and don't want to experience a dip in performance although you will reduce autophagy activity so decide what you want to prioritise (this is a common theme, and it seems you have to choose: high athletic performance OR longevity, you can't have both). 

And I did take some digestive enzymes with my first meal to help my stomach deal with food it hadn't seen in nearly a week! 

Your other options are foods that are easily digestible so juices, smoothies and soups are a good option.

Different Types of Fasting & Ongoing Maintenance

If you're not up for the NCLF fast or perhaps your Doctor has advised against it, there are other types which are summarised below in a table from Ben Greenfield Fitness.

For ongoing maintenance I use Intermittent Fasting on a daily basis, a 24 hour caloric liquid fast or CLF (using fatty coffee, juices, smoothies and bone broth) and a prolonged 3-5 day NCLF like the one I just completed 2-4 times per year. As I learn more I will also try to stay in ketosis as much as possible by following a more ketogenic diet.