The almost unbelievable benefits of fasting

I've put together a combined list of benefits of fasting and included my own personal recommendations for how to incorporate it into your daily life.

The almost unbelievable benefits of fasting
Photo by حثل / Unsplash

Why all the hype about fasting, what are the benefits and should it become a regular practice for most people?

In 2012 the BBC programme Horizon produced and aired a show called Eat, Fast, Live longer. My wife and I watched it and found it compelling. Incidentally, it coincided with the birth of our first child and the year that we both stopped going to the gym! It would be eight years before I started getting back into shape. However, the programme had sewn a seed and had started a worldwide trend. Newspapers picked up on the programme and the hype grew.

The programme explored the relationship between calorie intake and longevity. Specifically, the programme picked up on a scientific paper published in the journal Cell Metabolism examining the effects of calorie restriction and how it leads to increased lifespan in mice. The programme went on to interview some of the oldest living people and saw how few calories they ate compared to the average person. It ended with Michael adapting what others were doing to create a simplified diet that allowed him to live a fairly normal lifestyle. It became known as the 5:2 Diet, or as Michael called it, The Fast Diet.

The journal article concluded that Fasting:

helps reduce obesity, hypertension, asthma, and rheumatoid arthritis. Thus fasting has the potential the delay aging and help prevent and treat diseases.

Since 2012 a whole body of research has begun and continues to this day to examine the effects of fasting with new scientific articles coming out almost weekly. It is being studied to examine its benefits for curing cancer and for protection against cosmic radiation during multi-year expeditions into space.

The Fast Diet

The original 5:2 diet book written by Dr Mosely explains the amazing health benefits of fasting and how to incorporate it into your daily life.

Buy The Fast Diet from Amazon

The Conspiracy

Again not a real conspiracy, but a form of natural healing, that may or may not have been knowingly suppressed by the medical and pharmaceutical community. I'm particularly interested in our body's ability to heal itself using cheap or free methods without resorting to expensive pharmaceuticals that often come with severe side effects.

Aside from this I was practising and talking to others about fasting long before 2012. In 2000 I started fasting about 36 hours a week and continued to do so for about a year. The reason largely comes down to two passages in the Bible.

When you fast, do not look somber as the hypocrites do, for they disfigure their faces to show others they are fasting. Truly I tell you, they have received their reward in full. But when you fast, put oil on your head and wash your face ...
--- Matthew 6:16-17 (NIV)

This passage, spoken by Jesus, says when you fast. Indicating that those hearing Jesus were expected to be fasting at some point.

Then John’s disciples came and asked him, “How is it that we and the Pharisees fast often, but your disciples do not fast?”
Jesus answered, “How can the guests of the bridegroom mourn while he is with them? The time will come when the bridegroom will be taken from them; then they will fast.
--- Matthew 9:14-15 (NIV)

This additional passage speaks of the fact that Jesus will be taken from them, referring to the disciples and that once he was taken, then they would fast. Jesus was taken from the Earth at his ascension and so now is the time for fasting.

Then you can add to these passages others that demonstrate people fasting, including Jesus himself, also the apostles Peter and Paul.

Some Christians would argue with me that we should not be fasting because Jesus was not taken from us but lives inside of us. I don't see much point in this translation, it is an excuse not to fast, but clearly, the passage indicates there would be a future time when fasting would be done and I don't believe in a future where Jesus will be any more "taken away" than he is right now. So I believe now is the time for fasting.

Someone else has stated to me that:

Fasting is the 'F' word of the Bible

I'm not sure what they meant by this, but if the 'F' word is something that you should not talk about then perhaps they mean that fasting should never be talked about. Maybe they meant that it should not be practised. I'm not sure, but somehow fasting had received a bad rap from certain segments of the Church.

On this occasion, science came to the rescue!

Intermittent Fasting

Intermittent fasting, also known as Time Restricted Feeding (TRF), is essentially a generic name for a category of fasting into which the 5:2 diet falls. It refers to a regular practice of not eating for a certain period of time (up to 24-36 hours), or in the case of TRF, only eating within a certain time window.

Intermittent fasting and TRF come with their own notation. 5:2 means eating normally five days a week and fasting two days a week. 18:6 means fasting for 18 hours and eating within a six-hour window.

Alternate day fasting is a special case that refers to eating one day and fasting the next day. I'm not sure many people practice this because our weeks are an odd number of days meaning that fasting days would be different every week and therefore harder to stick to because of social commitments.

5:2 was the diet suggested by Dr Michael Mosely as offering the best balance for him. Something that he could commit to long term. He would fast Mondays and Thursdays and eat normally the other five days. He says in the forward to his updated book that he now follows 6:1, fasting only one day a week, because he didn't want to lose any more weight, whilst still gaining the other benefits from fasting, which we'll come to later. 4:3 could be an option for those with more severe problems and looking for a quicker fix. As a regular practice, those are what I'd consider the best options.

TRF allows you to benefit from fasting without fasting longer than a few hours. TRF always considers the eating/feeding window within a 24 hour period, and generally, the options are 16:8, 18:6, 20:4 and 22:2. 22:2 goes by the special name of OMAD (one meal a day). As the benefits of fasting increase with the period of time that food is not being consumed then OMAD is in theory the best for our health. The problem is that you still need to consume all your calories otherwise you will lose weight, and some people want the benefits of fasting without losing weight. Getting over two thousand calories in a single meal is not easy.

I practised OMAD for approximately one year. At the time I didn't have a name for it, and wasn't aware that it was even a thing. I was skipping breakfast anyway because I would leave for work at 6am and then I would just have a carrot and a paleo (fruit and nut) bar for lunch which was probably no more than 100 calories. In the evening I would eat whatever the rest of the family was eating. During this year I did not lose any weight, but I was sitting down for about 12 hours a day and doing no exercise. This shows that maybe you don't need as many calories as you think, especially if you lead a sedentary life.

At the other end of the spectrum is the 16:8 routine which allows you to fast completely from 8pm until the following day at 12pm when you can enjoy lunch and around 6 or 7pm you can enjoy your evening meal. So you are only skipping breakfast, avoiding snacks, and getting 16 hours of fasting every single day. I have been doing this together with my wife now for the last two years, although we still eat breakfast on Saturdays. Neither of us have lost any appreciable weight following this routine and our BMIs are both over 25. However, we continue this because of the benefits of daily fasting.

The keto diet

In 2020 I discovered Keto. I wasn't looking for it, but I heard other people talking about it and how effective it was. It was the year of the Coronavirus and I was looking to improve my overall health. I bought two books by Dr Mercola called Effortless Healing and The Ketofast. Dr Mercola also has other related books such as Fat for Fuel and the Fat for Fuel cookbook.

Effortless Healing

I highly recommend this book from Dr. Mercola. It has transformed my life causing me to take control of my health and that of my family.

Buy Effortless Healing from Amazon

Why is keto relevant to fasting? The keto diet (or ketogenic diet) refers to the body's production of ketones which occurs when the body is in a fasted state. Ketones are responsible for several of the benefits we experience during fasting but they only start to be produced after about 12 hours without food. If we eat anything after 8pm and have breakfast before 8am then we will never produce ketones. When starting to fast, or starting on the keto diet, then it may take a longer period of time for the body to produce ketones. To produce ketones the body needs to reduce the blood glucose and insulin and this takes time.

The keto diet tries to mimic the effects of fasting without actually fasting. You instead eat a diet consisting of about 70% fat, 25% protein and 5% carbohydrates. By limiting the carbohydrate intake, the body does not get an insulin and glucose spike after eating. Many of the benefits of fasting come from ketones and these are produced when the body has low glucose and insulin levels. Glucose enters the bloodstream after we eat a meal with carbohydrates and insulin is produced in response to the glucose in our blood. The keto diet, therefore, eliminates carbohydrates from your diet whilst allowing you to consume fats and proteins throughout the day.

Dr Mercola originally thought that the keto diet was the perfect lifestyle diet giving the benefits of fasting every day whilst allowing the normal consumption of calories. However, he discovered that the keto diet is too restrictive in that fruit and some vegetables are not allowed because of their high fructose content, and thus the body missed out on vital nutrients.

I tried the keto diet for about two months in 2021 and at this point I had started doing sport again. Now I was burning almost 800 calories daily through sport but was not able to consume enough calories because of the restrictions. It also did not fit in easily with our family life. And add to that, that I'd already lost weight through exercise getting down to a BMI of about 24, but I did not lose any further weight whilst doing the keto diet. These factors caused me to stop following a keto diet but I was now armed with the knowledge that fat and protein could be consumed without breaking a fast.

Metabolic Flexibility

Dr Mercola wrote the book Ketofast which I read to find out how he recommended combining keto and fasting for optimal health. I wasn't particularly taken by the book itself, it was light on details and often referred to other books that he'd written. The general idea was good; to combine keto and fasting and also feasting. By alternating on an almost daily basis the fasting and the keto and the feasting, then the body cannot adapt to any particular norm and will become more flexible operating at peak performance. Feasting in Mercola's language does not refer to gorging yourself on cake and ice-cream, rather it is slightly increasing your carbohydrate intake to about 125grams over the day which is still quite low, about half as many as is in a large pasta dish.

Dr Mosley and Dr Mercola both talk about fasting not as the complete elimination of calories, but as a severe restriction in calories for the chosen period. The favoured restriction seems to be about 500 calories or about twenty-five per cent of your normal calorie intake. This is what Dr Mosely proposed for his original 5:2 diet plan and what Dr Mercola also recommends.

When I started alternating keto, feasting and fasting, alongside the regular cardio that I was also doing, then I started to see the fastest reduction in weight that I'd seen in a long time, and my body weight went below the plateau that had developed following only keto and exercise. My weight went to its lowest level in over twenty years and my body fat percentage and BMI also moved into the healthy range. I continued this for about six weeks up to December 2021. I ate normally or possibly more than normal in December but only put on about 1kg. In January and February, I continued the fasting routine for another 6 weeks but no longer with the keto element.

For the last two months I have eaten normally and put on about 3kg. Both during the ketofasting and beyond I continued the daily routine of not eating before lunch, which on school days is often 2pm so that's about 18:6. If I consume my final meal at 6pm then I can even manage 20:4.

My final word on keto was the revelation that you could consume some calories without the benefits of fasting being broken. Butter and coconut oil are particularly good and can be consumed in larger quantities when mixed together to form a Bulletproof™ coffee. I now regularly make such a coffee in the morning to stave off any hunger pangs. Dr Mercola recommends consuming Psyllium husks with water although I only found this necessary on fasts longer than 24 hours.

Fasting Benefits

Since the research on fasting really took off in the last ten years, more and more benefits keep being discovered. I've put together a combined list taken from multiple sources for all the measurable benefits of fasting. At the end I summarise the fasting benefits as the list includes a lot of mechanisms without reference to the actual benefit.

After 12 hours:

  • Blood insulin levels drop and become stabilised
  • Ketone production starts

After 18 hours:

  • The body starts to burn fat
  • Ketones are measurable now
    • This causes inflammation of blood vessels to decrease
    • And causes DNA to be repaired
  • Human Growth Hormone (HGH) is produced
  • Brain-Derived Neurotrophic Factor (BDNF) is produced
    • This causes brain cells to be repaired
  • Cells start being repaired as Autophagy begins
  • Exercise can accelerate the process

After 24 hours:

  • Autophagy increases
    • Process of repairing cells begins
    • Cell debris cleared or recycled
  • Ketones increase
  • HGH/BDNF increase
  • Hormone signalling molecules change:
    • AMPK up (fat burning),
    • mTOR down (fat storage),
    • NAD+ up (energy)
  • As NAD+ increases Sirtuin increases which is strongly linked to longevity

After 48 hours:

  • HGH has increased fivefold along with BDNF
  • Ketones and Autophagy continue
  • Stem cell function improves
  • Mitochondria function improves
  • Brain repair, longevity, wound healing and cardiovascular health improves
  • Lowered insulin
    • Reduced inflammation
    • Repair cardio-vascular issues

After 72 hours:

  • Deeper Autophagy
  • More cleanup
  • Repair of misfolded proteins
  • Removal of low-quality cells
  • Regeneration and rejuvenation of cells
    • White blood cell strengthening
    • Reduce damage caused by Chemotherapie

After 120 hours:

  • No new changes
  • More time with other improvements

Overall health benefits

Cardiovascular Health

Dr Pradip Jamnadas, Cardiologist, summarises the benefits that he has personally seen in his clinic as follows:

  • Decreased blood pressure / cured hypertension
  • Reversed Type 2 diabetes
  • Weight loss
  • Improved mental clarity
  • Stronger heart muscles
  • Reduced frequency of trips and falls
  • Reduced dementia risk
  • Balanced hormone function

Alongside these, there are the added benefits of improved self-control and the resetting of eating habits.

Autoimmune Health

One of the longest advocates of fasting for health has been Dr Alan Goldhamer, who in 2001 authored a scientific paper on the use of fasting to cure hypertension. From his TrueNorth Health Clinic in California, he has helped over 20,000 patients through their residential nutrition programme where a combination of fasting and healthy eating has seen people cured of autoimmune disorders including Arthritis, Lupus, Colitis, Crohn’s disease, Asthma, Eczema, Psoriasis, and environmental allergies. These benefits are on top of the cardiovascular benefits. Dr Goldhamer's recommended nutrition plan involves eliminating all sugar, oils and salts, a so-called SOS diet.


Fasting has been shown to help in the treatment of and maybe even cure cancer. The study used more of a keto style diet so that the body was starved of carbohydrates. Without carbohydrates the blood glucose reduces and the cancer cells are effectively starved. This is because cancer cells can only use glucose for fuel whereas normal cells can also metabolize fat. Cancer cells in fact have ten times the number of insulin receptors as normal cells making them ten times more effective at using the energy from glucose than normal cells. This has been known since 1924!

Fasting or special diets have usually only been used in combination with other treatments such as chemo-therapy but the evidence reveals an improved survival rate of patients on such diets. Given that it's been known since 1924, isn't it strange that no one thought to remove sugar and carbohydrates from the diets of cancer sufferers until now?

More than the direct benefits of killing cancer cells, fasting has also been shown to improve the body's response to chemo-therapy making the treatment more effective at killing cancer cells whilst protecting the white blood cells from being killed themselves.


A reduction in the biomarkers related to dementia risk has been noted in the medical literature. It is well-known that increased blood glucose levels lead to an increased risk of developing dementia. Fasting resets the blood glucose levels. Additionally, BDNF is protective of brain cells and aids in their growth and reproduction. It is known that increased levels of BDNF are associated with a decreased risk of dementia. Fasting for only 18 hours will already increase the levels of BDNF in the body.

Other literature refers to a positive effect of coconut oil and specifically MCT oil which is popular in the keto diet as a healthy source of fats. MCT oil is known to increase the production of ketones and medical studies now show that there is a correlation between consumption of MCT oil and the severity of dementia, in some cases causing a significant decrease in symptoms.


Some seizures are caused by an inability of the brain cells to metabolize glucose. When these people switched to a keto diet their brain cells metabolize fat instead of glucose and this prevents the seizures. Some patients have noted a 10-fold reduction in seizures compared to using prescription drugs and a 30-fold reduction in seizures compared to using no drugs.

Fasting in Practice

The benefits of fasting are so huge that it cannot be ignored from a health perspective, add to this the words of Jesus "they will fast" and "when you fast", and it becomes hard to explain why we shouldn't fast on a regular basis.

I have been fasting 18 hours a day for five or six days a week now for several years. This will provide me with some of the benefits of fasting. I recommend that everyone do this as a minimum, it really is very achievable.

Secondly, I'd recommend adding a 24 hour fast into the mix to increase the benefits. I have recently started making this a weekly habit again. The 24 hour fast will start straight after lunch on one day and end with lunch the following day. As I am already skipping breakfast then I am really only missing one meal. By adding in a Bulletproof™ coffee then it is very easy to do.

Thirdly, I will be doing a two day fast once a month. This is my own personal goal to completely reset the digestive system and to experience an increase in all the beneficial effects of fasting. If you're following 5:2 then maybe you don't need this step. When I'm ready for a challenge then I will do a five day fast once or twice a year, just to extend the benefits even further.


Fasting can result in decreased muscle mass. This is a misconception that is easy to understand because those who fast usually do see decreased muscle mass. Even researchers can attribute the loss in muscle mass to fasting. However, recent research suggests that muscle mass reduces due to inactivity and not due to reduced food intake. Over short durations of less than five days, muscle mass was retained simply by incorporating some light exercise.

Fasting gives me headaches. The headaches are caused by withdrawal from various addictive substances, often caffeine or sugar. Although caffeine is not recommended during a fast it can be consumed in moderation if you wish. Alternatively, try some fruit or herbal teas (without sugar), or simply water with a dash of lemon juice. Going to bed early often helps at the end of the first day.

Fasting is dangerous. There is a misconception that fasting is too extreme and causes undue stress on the body. That seems to be why many doctors will not recommend it. The other reason is that they do not believe patients will actually stick to a fasting plan. Certainly, some people would benefit from medical supervision if they can get it. Anyone with cancer or seizures or pregnancy should see a doctor if they are wanting to fast for longer than 24 hours. Restricting calories to 500 for two days of the week should not be a concern for anyone who is obese or overweight.

Fasting leads to eating disorders. There is some correlation between those fasting and those with eating disorders. Meaning people who have eating disorders may convince themselves that they are participating in a healthy form of fasting. The important thing is to ensure that the required calories are being consumed throughout the week. If someone is consistently consuming too few calories then they will eventually become dangerously underweight.

Fasting decreases my sporting performance. It is true that whilst fasting your body lacks energy. However, your body is producing Human Growth Hormone and that is positive for recovery and muscle growth. The best way to fast as an athlete is to work out just prior to breaking the fast. The muscles will feel weak but will quickly be strengthened afterwards. If going into a competition then taking carbs on board a day or so in advance is recommended. Athletes who regularly follow the keto diet have reported a loss in performance when the body tries to use fat for fuel instead of sugars.

Weight will be quickly put back on again. This is true of fad diets. Fad diets meaning those that temporarily change your eating habits and see you quickly lose weight. The problem is that they are temporary. The other problem is that they do not integrate well into family life. Fasting could not be simpler, it is healthier than most fad diets and can be done long term with no down sides. Those who integrate it long term into their lifestyle lose weight and keep the weight off.


Fasting should absolutely be integrated into your lifestyle. Just skipping two meals a week can have amazing health implications down the line. Experiencing fewer illnesses and avoiding diseases should be enough motivation for anyone. Add to that the muscle building and brain building effects and even young people should be convinced.

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