Fasting is as old as the hills. Plato said that he fasted for greater mental and physical efficiency. Hippocrates and Paracelsus, both advocated fasting. With the former saying that “everyone has their own physician inside them” and “that to eat when ill is to feed the sickness”. Plutarch a middle Platonist philosopher said, “instead of using medicine, fast a day”. Wise words.
In the West, fasting is no longer part of our culture. Indeed, we are subject to constant bombardment to eat. We eat to celebrate, we eat for a treat, we often eat six times per day. The behemoths of the food industry shower us with messages telling us to enjoy healthy snacks. Breakfast is lauded as the most important meal of the day and the phrase “Eat a Good Breakfast-Do a Better Job” launched many breakfast cereals onto our plates. Our culture revolves around continual eating, which is considered by most people to be an entirely healthy choice.
How did we change from eating one meal a day as the Romans did, to a three or even six meal a day society? The mantra of three meals a day is a modern construct, ‘breakfast’, literally ‘to break the night’s fast’ entered the English language in the middle ages and breakfast became ubiquitous only in the days of the industrial revolution. In the middle ages, fasting was common and a two meal a day regime was widespread. The present habit of all-day eating is related in no small way to the obesogenic environment that we have created and the ubiquitous food advertising that we are subject to. But, the loss of intermittent fasting from our lives may be impacting adversely on our health and contributing to the obesity pandemic.
Fasting has significant health benefits, in terms of metabolism and cellular health. It is also a powerful tool for weight loss and long-term weight control. We shall explain why the ancient practise of fasting is a sensible addition to anyone’s nutrition plan. In the 21st century, we have lost many of our vital links with religious fasting and our forefathers healthy fasting habits. A generation of people think fasting is uncomfortable, unnecessary and dangerous. It is not and they are very wrong. Quite the opposite, fasting brings our bodies into a state of regeneration and repair, critical for health and well-being.
Terms related to Intermittent Fasting
• Fasting; a period of time when no food is taken except for unsweetened black tea, coffee and water. To be perfectly clear, what we mean by fasting is variable intermittent fasting, and for simplicity called fasting from this point on.
• FastSpan ® is the period between the end of the last meal of the day and the start of the first meal the following day
• EatSpan ® is the time from the start of the first meal of the day, to the end of the last meal of the day.
Intermittent Fasting versus Calorie Restriction
Fasting is completely different from calorie restricting, or calorie counting. And to understand this, food and meals are anything ingested, apart from water and black tea and coffee. At Whisperer HQ, we call and count all snacks, a meal.
A calorie restriction diet involves long-term reduction of calories by 20-40%. This can be achieved by changing the type of food eaten, reducing the amount of food eaten, or a combination of both. Importantly, the number of meals each day is either the same or increased. Intermittent or periodic fasting involves periods of 12 hours or more, when no food or drink is taken. In the whisperer-plans, fasting periods are interspersed with keto cycling meals, and meals that are not calorie restricted. A sort of anything, but not everything lifestyle, that suits and adapts to modernity well.
In calorie restriction, hormonal homeostasis slows the body down, reduces body temperature and reduces the energy consumption or basal metabolic rate (BMR). Your hormones will perceive a threat of starvation and will act to conserve energy. Weight loss suddenly grinds to a halt. In fasting, your hormones react in a totally different way. Instead of shutting your body down, they allow repair and regeneration. Fasting increases your stress resistance, suppresses inflammation and improves blood glucose regulation.  Fasting improves these health indicators, and they carry over into the fed state. This has the effect of improving mental and physical performance and increasing resistance to disease.
Is Intermittent Fasting Good for You?
Let’s look at the 10 commonest misconceptions around fasting;
- Three meals a day is best. Wrong, reducing EatSpan and lengthening FastSpan increase fat burn and weight loss.
- Missing a meal puts the body into starvation mode. Wrong, intermittent fasting does not put the body into starvation mode. Calorie restriction puts the body into starvation mode, which makes us cold, hungry, sleepy and miserable and turns down our metabolism.
- Breakfast is the most important meal and gets your metabolism going. Wrong, breakfast breaks the benefits of the overnight fast. There is no evidence that it helps with fat burn. In fact, it turns the fat burn off, making us store fat, under the influence of our fat storage hormone, insulin. The more carbohydrates for breakfast, the more severe the insulin rise, and the greater the inhibition of fat burning. If you have to eat breakfast, at least go to work on an egg. (less insulin release)
- Eating small meals more frequently turns up the metabolism, thus burning more fat. Wrong, it increases insulin release and fat storage. It inhibits fat burning.
- Fasting causes hunger. Wrong, fasting prevents hunger. Hunger gets worse with calorie restriction, multiple meals, and both refined and super-refined carbohydrates.
- Fasting causes harm. Wrong, our bodies were designed to fast, and we survived intermittent fasting for 200,000 years. Fasting improves general health indicators. It promotes good mental and physical health and improves our spirituality. It is highly correlated with human wellness and longevity. 
- Fasting causes cell damage. Wrong, fasting is associated with healthy cell renewal, reduced aging and cell renewal, called autophagy.
- Fasting can harm our brain as our brain needs exclusively to fuel on glucose. Wrong, our brains can survive happily on ketone bodies, produced during fasting.
- Fasting will upset blood glucose. Wrong, insulin levels and insulin resistance are reduced, fat burning increased, with major improvements in blood glucose regulation.
- Fasting does not protect our cells and brain. Wrong, studies show cell renewal and autophagy as well as possible protective measures in central nervous disorders like epilepsy and possibly dementia.
THE INTERMITTENT FASTING BENEFITS INCLUDE BUT ARE NOT LIMITED TO:
• Reduced weight
• Reduced visceral fat
• Reduced insulin levels and insulin resistance 
• Reduction in all the features associated with metabolic syndrome including bad cholesterol
• Increased uric acid**
• Increased Human Growth Hormone (HGH or somatotropin). It increases fat burn directly on fat cells 
• Increased autophagy; renewing cellular organelles and inducing the anti-aging process in all cells including the brain
• Increased mitophagy, or mitochondrial renewal. Conversely, we know that heart mitophagy is reduced by diabetes and age
• Increased cognition and clarity of thought
• Improved short term memory
• Reduced free radicals, reducing oxidative stress
• Increased stress resistance at the cellular level
• Reduced inflammation in many long-term conditions, such as asthma
• Reduced gut inflammation and increased motility
• Reduction in blood pressure
• Reduction in resting heart rate
• Reduction in C-reactive protein, a marker of inflammation
• Activation of sirtuins, in a similar way to resveratrol, reducing oxidative stress and increasing mitophagy
• Increased gut microbiome diversity
• Fasting consistently increases lifespan in animals
• May have a role in cancer prevention, treatment and tumour suppression
• May have a role in delayed aging 
We know that when we avoid refined carbohydrates, introduce intermittent fasting, reduce meal numbers, increase FastSpan and reduce EatSpan, we get positive effects on both our mental and physical health. We straighten out our hormones for wellness, longer healthspan and longer lifespan. We know that the induced autophagy is associated with reduced aging. And we are able to achieve permanent weight loss.
**Raised uric acid levels may have some anti-inflammatory effects. [4,5] It should be noted that gout may occur as uric acid goes up, and when it comes down. Uric acid directly competes for secretion in the urine in the kidney with ketone bodies. So, as ketone bodies increase, uric acid secretion reduces and blood uric acid rises. But in the fasted state in studies, gout did not occur.
How does Intermittent Fasting work?
The macronutrients, fat, carbs and protein are broken down by digestion into their constituent parts, fatty acids, sugars, and amino acids and then absorbed from the small gut into the bloodstream. When glucose is taken in excess of that required for immediate energy and our glycogen stores are full, the excess blood glucose is stored as fat. Insulin will mediate this. Insulin also mediates the building of muscle; again, any spare amino acids will also be stored as fat. So, our normal fed state is one of circulating insulin, with glycogen stores fully replenished. Our insulin peaks and then fades back down.
Our absorbed glucose is now stored away, and the blood glucose falls into the normal range. When refined carbs are eaten, the blood glucose falls before the insulin has stopped circulating. The insulin overshoot can cause a period of relatively low blood sugar, making us hungry and angry. The word “hangry” combines them both, explaining the peak in road rage at 6 o’clock in the evening.
Without more food the circulating blood glucose gets slowly used up. But, should this go on, the blood glucose would fall to dangerously low levels. To prevent this, glucagon, a hormone from the pancreas is released, increasing the blood glucose to normal levels.
This represents our natural fast from supper to breakfast. Here we go from the storage of glucose (insulin-mediated), to glycogen breakdown (glucagon-mediated). Glucagon mediated glycogen breakdown maintains our blood glucose in spite of the glucose “pull” from our red blood cells and brain. At only 2% of our body mass, our brain uses 20% of the body’s daily energy burn. That is 400 calories, equating to our whole glycogen liver stores of 100 grams. So, glucagon keeps our blood sugar ticking along from our glycogen stores. It also is able to top up this process by making glucose from fats and amino acids, called gluconeogenesis. Most organs and cells use fats and proteins for energy directly; the brain and red blood cells are exceptions. Thanks to glucagon, there is sufficient glucose in the blood to provide for their needs.
If at this stage, we eat, the cycle starts all over again. If we continue to fast, then;
After 12-48 hours
Our glycogen stores are now depleted, and our hormones now switch us into full ketogenesis. That means, “ketone-making”. The ketone bodies produced are acetone, acetoacetate (AA) and beta-hydroxybutyrate (BHB). The brain now switches to 70% ketone use for its energy. So, the brain uses 280 calories from ketone bodies, AA and BHB which can unlike other macronutrients cross the blood-brain-barrier. Simultaneously, gluconeogenesis continues producing new glucose from fats and muscle, as required. This can trickle out 80-100 grams of glucose per day into our blood equating to 320-400 calories. Our hormones have changed our metabolism to protect us with at least 200-400 calories to spare of glucose. And it did this without any requirement for dietary macronutrients of any type. Interestingly there is less oxidative stress around when our brain is 70% powered on ketones bodies. Our body maintains a beautiful balance though hormonal homeostasis. It’s how we’ve lived for 200,000 years and our genes have encoded us with the ability to fast and thrive. Fasting is a time for repair and regeneration.
After 2-5 days of fasting
Circulating insulin deceases significantly by 20-30% and Ghrelin (our hunger hormone) decreases, day-on-day resulting in much less hunger. Repeated fasting will not only reduce insulin resistance, but also reduce your chance of developing metabolic syndrome and type 2 diabetes. At the same time, there is a reduction in insulin resistance and leptin resistance. Autophagy will increase, replenishing our cells and making our gut and skin healthier. Our immune system cells are renewed. Autophagy is associated with slowed aging. This may, particularly in men, produce skin shrinkage as the weight comes off.
How to Start Intermittent Fasting
If your body is trained to use fat as a fuel, you can fast tomorrow. And provided you have sufficient fluid; you can fast safely for days. If your body is not trained to burn fat, you will struggle to fast for more than 12 hours. If your body is carbohydrate addicted, your fat engine is dormant, and you are fat fuel inhibited. In real world terms, this means that long term eating of refined and super refined carbs, has caused your fat fuel engine to seize up, through lack of use. Fat burning has ceased. The good news is that the fat fuel engine can be reignited and once you do this, you will start to burn fat, and get all the benefits of fasting and lose weight. This process is called fat adaptation.
So, before fasting begins, we must fat adapt our bodies. We have a further blog specifically on how to achieve fat adaptation. Fat adaptation may take some time, but it allows us to access the pleasures and other benefits from fasting. Another factor in your success, is that you will find it hard to achieve this without support from your friends and family.
Intermittent Fasting Rules
As always, discuss this with your doctor who will be able to support your plan to get lighter, fitter and healthier. Talking to your doctor is also a must if you are on any medications or have any co-existing diseases. For example, diabetes or hypertension may require a reduction or even a cessation in treatment, and it must be your doctor who guides you through this reduction in treatments. How exciting would that be!
• Fasting is an ancient practise; we have lost connection with the fasting our forefathers practised
• Fasting should come after you have become fat adapted
• Fasting is not dangerous
• Fasting is associated with positive changes in our brains
• Fasting improves health markers
• Fasting improves cellular health and turnover, or autophagy
• Fasting is good for the gut microbiome
• All three macronutrients can produce glucose to protect our red blood cells and brain
• Our brain can survive on a combination of ketone bodies and less than 20% glucose
• We do not need any refined or super-refined carbohydrates in our diet and these should be discarded except for rare treats
• With 3 litres per day of fluids we can fast safely for days or weeks. Build up slowly
- de Cabo R, Mattson MP. Effects of Intermittent Fasting on Health, Aging, and Disease N Engl J Med. 2019;381(26):2541-2551.
- Heilbronn LK, Smith SR, Martin CK, Anton SD, Ravussin E. Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism. Am J Clin Nutr. 2005;81(1):69-73.
- Hartman M, Veldhuis J, Johnson M, augmented Growth hormone secretion, frequency and Amplitude mediate enhanced GH secretion during a two day fast in normal men. J of Clin End Metab. 1992. 74;(4) 757-765.
- Ames BN, Cathcart R, Schwiers E, et al. Uric acid provides an antioxidant defense in humans against oxidant- and radical-caused aging and cancer: a hypothesis. Proc Natl Acad Sci USA.1981;78(11):6858-6862.
- Lloyd-Mostyn R, Lord P, Glover R. Uric acid metabolism in starvation. Ann. Rheum. Dis. 1970; 29; 553.