Intermittent and extended fasting with the keto diet

Please visit our Disclaimer/disclosure page

Extended fasting

I’ve been on keto and reached my goal weight so what now?

As I mentioned, in this video on the keto diet, I do not believe that keto should be a way of life but rather that one should have a weight range that you set yourself. When your weight approaches the lower of the range then, I believe you should stop keto and go onto a low carb diet and purposely allow you weight to drift up until you approach to upper level of the range and then act to bring it down again.
Why do I think this? Because our bodies have evolved to cope with times of feast and times of famine so it makes sense that we should allow our physiology to experience and respond appropriately to both scenarios.

I have set my weight range to between 80-82 kgs. I reached my goal weight of 80Kg about a month ago so I have been off keto and on a low carb diet since then and I have purposely allowed my weight to drift upwards towards the upper limit of my desired weight range which is 82 Kg. So now it is time to act to counter this. I have considered two pathways back to my desired weight, 80 kg, currently I am 82 kg.

  1. Is to go back onto the keto diet for a month or so until I get back to my goal weight. If you want to learn more about the keto diet then watch this video.
  2. Is to do an extended fast to, get back to or close to, my goal weight as quickly as possible and explore the health benefits of extended fasting..

I’ve decided to put fasting to the test. I am starting a 5 day fast tomorrow and I will share my experience with you day by day. Why did I choose fasting? Because I have read of the many reported health benefits of fasting, in my case high blood pressure, pre diabetes 2 and a recurrence of prostate cancer. In a moment I will list the many reported health benefits of fasting. During the fast I will record some of my vital signs like blood pressure, blood sugar, my weight, my body fat percentage each day. And each day I will discuss how I am feeling. I will also try and test my mental and physical ability. At the end of the video I will summarise my readings in the form of a table.

I must stress that fasting is not safe for everyone and so before embarking on any fasting it is essential to check with your medical professionals and to do your own research to make sure that it is safe for your situation. I found this book, ‘The complete guide to fasting” by Dr Jason Fung, very comprehensive and most helpful.

So what are the reported health benefits of fasting? I’m going to keep this brief but many of the benefits are also derived from ketosis because prolonged fasting results in ketosis. If you are interested in me expanding on any of these points please leave a comment below.

Health benefits of fasting

  1. Weight loss – this is obvious if you do not consume calories you will lose weight. And if you fast long enough to enter ketosis you will lose body fat. Losing fat has many health benefits mental and physical. Apart from feeling better, looking better, more energy and greater self-esteem.
  2. Lowering of high blood pressure. I have already seen the effects of this while on the keto diet so I am keen to see how fasting affects this metric,
  3. Lowering of blood sugar and insulin thereby reversing insulin resistance and possibly reversing diabetes 2. Again I have already experience this whilst on keto.
  4. Lowering of blood lipids including LDL or ‘bad’ cholesterol.
  5. Increases energy and mental ability.
  6. Reversing of the ageing process and extending life – ketones may reverse blood vessel ageing.
  7. Fasting may help prevent Alzheimer’s disease.
  8. Fasting may improve the body’s response to certain cancers. Many cancers need insulin and glucose for growth, fasting may starve them by lowering both of these. During fasting the body initiates a physiological process known as autophagy which involves the mopping up of accumulated debris such as damaged proteins and sub-cellular particles, much like spring cleaning. This may play a roll reducing inflammation, cardiovascular, Alzheimer’s and in cancer prevention.

Health benefits of fasting have been known for centuries, indeed the father of modern medicine, Hippocrates, was a strong advocate of fasting for a range of medical conditions and believed fasting allows the body to heal itself from within, the physician within as it were. This makes sense since the body has less to do if you are not eating. It no longer has to deal with digestion and assimilation of nutrients and ingested toxins and pathogens let alone any food intolerances are all eliminated and the GIT in particular has a chance to heal. The liver and kidneys have less work to do so they can catch up on things. All of this detoxifying, as it were, is supposed to lead to clearer and improved mental and physical capacities.

Daily fasting reports

Here are my reports written during my 5 day fast. At the end of the fast I produced a table summarising the results, see below.

Day 1.

Here is where we set some ground rules. I will only consume water (plenty), vitamins, minerals and 2-3 cups of black sugarless tea or coffee and the occasional glass of salt water. One thing I have learnt from the short fasts I’ve done while on the keto diet is that it is best to stay busy to get your mind off food. I believe hunger is at least 50 % mental conditioning. Each day I will offer a tip for coping with fasting so that is my tip for today – keep busy. I am currently renovating a bathroom so that should keep me busy throughout this fast. I am also keeping up my regular exercise regime which is 10 minutes of isometric exercise first thing in the morning followed by a 2.5 km walk and then another 2.5 km walk in the afternoon. I will record my maximum heart rate on these walks just to get an idea what is happening physically. I hope to get into ketosis quickly, hopefully starting tomorrow, the exercise will help. I also expect to see a large weight drop tomorrow of a kilogram or more. This will largely be water loss because I will be using up my glycogen stores and each gram of glycogen burned yields about 3 grams of water. The body usually hold about 400 grams of glycogen in muscles and liver so that is about 1200 grams of water which will be lost along with some minerals. So it is important to drink lots of water and supplement minerals and vitamins. Incidentally 1 gram of glycogen is about 4 calories so my body will have about 1600 calories of stored glycogen which I should easily burn in the first 24 hours of fasting and then enter ketosis.        

Day 2.

This is day 2 of the fast. I have been fasting now for 42 hours, it is lunchtime now and I am happy to say that I am not hungry. I have to say however that I did struggle a bit with hunger last night while Ann was preparing and eating her supper. That leads me to the fasting tip of the day; don’t watch people making or eating food. Also try not to smell food or read recipes.

As predicted yesterday I did have a large weight drop this morning of 900 grams ( mostly water I believe) and starting last night I had a thick fuzzy head and continuous thirst, a bit of ‘keto flu’  I suspect. So I believe that I am entering ketosis which means I am starting to burn fat. I expect that my weight losses from now will be of the order of about 300gms per day. Which I hope will be mostly fat. At 9 calories per gram of fat it means burning 9 x 300 = 2700 calories in the day which is achievable if I remain active. So that is it for today. Chat to you tomorrow.

Day 3.

This is lunchtime on day 3 of my fast, I have been fasting for 66 hours now. I recorded another large weight loss this morning 0.8 Kg half of which was probably water. My blood glucose however was seriously low first thing this morning at 3.2 mmols/lt. I felt a little shaky as well so I considered abandoning the fast or at least drinking some sugar water. But I decided to try first mobilising blood sugar with light exercise. And after my 10 minutes of isometrics my reading went up to 3.7 and after my 2.5 km walk it rose to a respectable 4.2 and I felt a lot better. So I was happy to continue fasting. This leads me to my fasting tip of the day, don’t try fasting without first consulting your doctor and it is probably not wise to go on an extended fast if you live alone. I would also advise that you have on hand the means to check your vital signs every day like a blood glucose metre, a blood pressure monitor, a scale (preferably a smart scale) and a means like a smart watch to record heart rate. That’s it for today, I will chat to you again tomorrow.

Day 4.

This is day 4 lunchtime and I have now been fasting for 90 hours. I feel no pressing need to eat anything. My blood sugar was low again this morning at 3.4 not as bad as yesterday and after my exercise it rose to 3.7. My blood pressure was also low this morning probably due to low blood volume which means I need to increase minerals and water. To try and overcome this I had a bowl of bone broth this morning, bone broth is apparently permissible on an extended fast. There is a good recipe for bone broth in this book which I mentioned earlier. In this regard on the first and second day I suffered a bit from muscle cramp and felt dehydrated, since then I have increased water intake to about 2 litres a day and I have been having a ½ teaspoon of Pink Himalayan salt per day and have not had any cramps since then. So my fasting tip for the day is to drink plenty of water and supplement minerals. Chat to you tomorrow.

Day 5.

This is day 5 and the last day of my fast. I will be having my first meal in a few hours so it is appropriate to talk about how to break an extended fast. The advice from the experts is to have a light snack an hour or 2 before your first meal to condition your gut to receiving nutrients and fibre again. So I have decided for my snack I will have a few nuts and then a small amount of tuna salad. I will now go onto at least a week of the keto diet and then consider moving to a low carb diet. So that is my fasting tip for the day start refeeding slowly and do not overload your gut.

So would I do it again? I have to say that I did struggle at times not so much from hunger but rather from the effects of low blood sugar, low blood pressure and a bit of nausea. I must say the bone broth helped a lot. Whether or not I would do it again all depends on the results of my next prostate cancer test, if that is favourable then yes I would consider doing a fast every 6 months or so but probably only for 3-4 days. If there is no benefit on cancer question then I will probably not do another extended fast because all the other health benefits I can get from the keto diet with a bit of intermittent fasting.

So let’s have a look at the table of my metrics during the fast.

Summary of recorded metrics over 5 day fast

Shop for books on fasting: Australia:

Shop for books on fasting: USA & UK:

Short Disclaimer/disclosure: As an Amazon Associate I earn a small fee from qualifying purchases. There is no additional charge to you. My videos/articles are for informational and educational purposes only, you should consult with a professional before attempting anything seen or done in my videos/articles. See full disclaimer above.

This this is the video discussion of the 5 day fast:

Leave a Reply