Research into fasting is getting more attention for a variety of disorder including auto-immune disease, hormone regulation, weight loss, cardiovascular disease and many more. It is important to note that fasting often doesn’t achieve overnight results but needs to be implemented consistently over a period of time for maximum benefits. This may involve long fasting periods or shorter intermittent fasting controls, depending on what is more practical for you or what your practitioner recommends.
True water fasting is without juices or light meals. This is not something we necessarily recommend as it has to be done under supervision and in our opinion should only be considered in healthy individuals whose bodies can handle the stress of a full fast, which generally is not the typical client in our practice.
This includes periods of overnight fasting ranging from 13 – 16 hours. This means you don’t eat anything for that period of time. It may mean having dinner at 5pm and breakfast the next day between 6-9am. You may still drink water, herbal tea, black coffee, but no chewing. Eating is concentrated inside the other 11 – 8 hours. You can aim to do this 2 – 4 times a week or whatever works for you. Even though it is hard at first, your body adjusts fairly quickly and it’s easier to do than true fasting, and really, it’s just eliminating snacking after dinner. It is best to stop eating/drinking at the latest 7 or 8pm at night.
Still very effective at giving the digestive system a break, allowing some much needed in-house cleaning of the cells (autophagy) and resetting the immune system.
OTHER VERSIONS OF INTERMITTENT FASTING
Dr. Mercola is a big proponent of intermittent fasting and has an even shorter window of 6 hours per day for eating. This can reduce meals from 3 meals per day to 2 meals per day.
Or Dr. Michael Mosley’s 5:2 diet which you can read about here.
Ketogenic and Keto-adapted diets are iso-caloric diets that mimic the effects of fasting (which is why we have included it here). We have to be clear here that we are not talking about just a high fat diet. We are talking about high fat, moderate protein, low carb diets. Just increasing fat in your diet does not constitute a ketogenic diet and can be very harmful to your health. We are also referring to ISO-caloric diets and not hyper- or hypo-caloric diets. These things need to be considered in order to achieve ketosis as it is the ketones that produce the effects of fasting.
As a matter of interest, drinking fat or stimulants does not register in the body as food and still produce the same effect as fasting. Examples include black coffee, green tea, ‘bulletproof coffee’ where you have butter/MCT oil/cream in coffee, butterball, etc.
The same does not hold true for juices (even if it is vegetable), smoothies, coffee or tea with milk (even nut milks), or eating fat such as avocado. For some reason the body loses the effects of fasting which indicates it registers this as food and initiates an insulin response, although not nearly as strong as when eating carbohydrates or sugars.
COMBINING KETOGENIC DIET WITH INTERMITTENT FASTING
This is another method that people have done with great success. It may not suit everyone, but can make it easier for those who are used to grazing a lot and not used to going without food for longer periods of time. Healthier people will be able to do this with greater ease. Others need to consider doing this along with a healthcare practitioner due to the amount of toxins that can be released during this process.
There is also a great podcast I did with Matt and Steve at ATP Science regarding Fasted Exercise and Intermittent Fasting that you can watch below:
EFFECTS OF FASTING ON OBESITY
Studies done on obese individuals after 48 hours of fasting showed a worsening of a lot of their markers and a lack of response in expected changes seen in lean individuals. This was interesting. The obese group showed increases in blood sugar, insulin, triglycerides, lipid oxidation and leptin, and a complete metabolic resistance to switch from glucose to fatty acid oxidation, whereas the lean group improved in all these parameters.
There would be other variables as well, but it’s important to note this as many overweight people would try this approach, get bad readings on their blood tests, and then be advised to stop doing what they’re doing as it is ‘dangerous for their health’, when it may simply be a case of metabolic resistance that needs to be approached differently. This particular study was only done over 48 hours which is a very short period of time.
Doing it slower, or more of a ketogenic or intermittent fasting approach may be better to stop the body from going into a ‘stress response’, but be aware that you are forcing the body out of its comfort zone into something it is not used to. It is especially important for those who hold a lot of toxins in their fat cells as well.
I often find reasons for this type of scenario when I run an Organic Acid Test.
This test provides information on whether a person has the ability to process fats as an energy source or not, and also the reason why this may not be happening. Correcting things from a biochemical and cellular level can often result in better outcomes in weight loss and other health issues when it comes to fat metabolism.
Receptors for insulin, leptin and many other hormones are also greatly down-regulated in obese individuals which mean they may produce more hormones or signalling molecules in response to specific triggers than is necessary.
EFFECTS OF FASTING ON THE IMMUNE SYSTEM
Mice studies have shown that repeated cycles of 2-4 days of complete fasting (no food) over the course of 6 months completely overhauled the immune system. All old cells were killed off and new immune cells were generated – a process called autophagia and mitogenesis. This holds great promise for auto-immune diseases. There are a few mechanisms involved here:
- Switches off PKA enzyme, linked to longevity and stem-cell proliferation
- Stem-cell stimulation and cellular regeneration
- Drop in IGF-1 growth factor linked to aging and cancer
- Apoptosis or self-destruction of old, damaged or unregulated cells
EFFECTS OF FASTING ON CHEMICAL DETOXIFICATION
Chemical pollutants and metals store in the fat compartments of the body which may include organ fat or more peripheral fat stores. Fasting has been shown in studies to mobilize chemicals and metals, showing up in large amounts in urine and blood samples whilst they were absent pre-fasting. For some compounds such as VOC’s (Volatile Organic Compounds), PCB’s and other persistent chemicals fasting seems to be the only way to get these chemicals out of the body where chelators are ineffective.
EFFECTS OF FASTING ON THE MITOCHONDRIA
This is an adaptive mechanism from ancestral DNA when seasonal changes really affected energy production such as winter times when foods were scarce. The glycolytic pathway is extremely down-regulated during times of low caloric intake such as fasting and mitochondrial energy production is up-regulated. The better adapted your mitochondria is, the easier fasting, calorie restriction or ketogenesis is. Struggling to stick to fasting, ketogenic diets or calorie restriction is a clear sign that mitochondria is very poorly adapted and not resilient to stress.
The well-adapted mitochondria will use carbon skeletons from fatty acid deposits to burn for energy and produce carbon dioxide and water in the process. The poorly-adapted mitochondria will probably break down muscle and turn it into glucose via gluconeogenesis in the liver in a desperate attempt to feed the glycolytic pathway.
EFFECTS OF FASTING ON CHOLESTEROL
During fasting cholesterol levels seem to increase slightly in one study. This occurred even after just one day of water-fasting. This may be the body’s regulatory mechanism where it derives energy from fat in the presence of glucose deprevation.
Dr. Benjamin Horne’s (PhD) research seems to indicate that the body feasts on LDL (bad) cholesterol during periods of fasting which could explain why cholesterol levels seem to go up slightly during fasting. Over a 6-week period though cholesterol levels decreased by about 12%. LDL cholesterol is extracted from fat cells for energy which then helps to improve insulin resistance and decrease insulin secretion by the pancreas.
EFFECTS OF FASTING ON LEPTIN
Fasting will cause a drop in blood sugar and thus a drop in insulin secretion, which will cause leptin levels to decline as well. Leptin is the hormone that is secreted by fat cells that tells the brain it is full or satisfied and doesn’t need any more food. As leptin levels go down after not consuming any food for a while, hunger sets in.
Leptin also induces the pituitary gland to secrete FSH and LH independent of GnRH (gonadotropin releasing hormone). FSH and LH are needed in females to produce healthy eggs. Prolonged fasting can cause a drop in leptin and thus LH (luteinizing hormone) which can cause a drop in progesterone production and fertility. This is often seen in extreme weight loss with absence of the menstrual cycle.
We are however talking about really extreme fasting here and not intermittent fasting.
Most people today suffer from leptin resistance with their bodies trying to compensate by secreting more leptin. As leptin seems to be involved in the onset of puberty it may provide another explanation why girls seem to be entering puberty earlier these days. It would correlate with increases in child obesity rates and diabetes as well. In these instances fasting and a drop in leptin will improve leptin resistance and excess estrogen production.
EFFECTS OF FASTING ON NEUROTRANSMITTERS
Caloric restriction increases ghrelin levels which in turn increases BDNF (Brain-Derived Neurotrophic Factor) after about 16 hours of fasting, and increases the resistance of neurons in the brain against dysfunction and destruction caused by oxidative stress, ammonia, quinolinic acid or high glutamates (just to name a few), and regenerates brain cells through a process called neurogenesis. This improves learning and long-term memory. BDNF may also be responsible for the glucose regulation and cardiovascular benefits we see with intermittent fasting and calorie restriction.
As we know most serotonin is made in the gut. Studies have shown that GDS (Gut-Derived Serotonin) synthesis increases during fasting and functions also in regulating bone formation and blood sugar regulation.
FASTING AND THE COMT GENE
This may be the one area where full on fasting may not be the best thing, at least not until symptoms here are under control and blood sugar is balanced. In general, fasting reduces plasma norepinephrine and glucose levels which returns back to base-line rates when fasting stops. But when fasted rats were exposed to psychological stress in one study, norepinephrine and glucose increased more dramatically than their fed buddies.
During fasting insulin drops and glucagon regulates blood sugar by releasing glycogen (stored glucose) back into the bloodstream. This prevents hypoglycemia. When glycogen becomes depleted, fat stores will be utilized or amino acids (from protein or muscles) will be converted to glucose via gluconeogenesis. All of these mechanisms regulate blood glucose. If glucagon cannot do its job for whatever reason, the body will compensate by releasing catecholamines such as adrenalin in order to stimulate glucose production and restore blood sugar homeostasis.
The COMT enzyme is responsible for breaking down and metabolizing catecholamine neurotransmitters such as dopamine, epinephrine (adrenalin) and norepinephrine. When these neurotransmitters build up due to a slowed COMT enzyme it can contribute to feelings of intense anxiety and insomnia. Those who are homozygous for COMT H62H and COMT V158M and are expressing it, need to be aware of this and experiment with different levels of intermittent fasting to see if they can find what works for them. This is where individuality comes into play and where one size does not fit all. In my opinion COMT homozygous does not mean you cannot use fasting or intermittent fasting, especially if you are not expressing it, but just that blood sugar regulation and stress coping mechanisms become super important for these individuals.
EFFECTS OF FASTING ON GENE REGULATION
Fasting has a tremendous role in gene regulation by down-regulating the expression of many inflammatory and disease causing genes such as the obesity gene (ob).
EFFECTS OF FASTING ON HISTAMINE
HDC (Histadine Decarboxylase) activity is very low after prolonged fasting. This may explain why those with inflammatory conditions such as arthritis and eczema experience improvement in their conditions with fasting. Fasting may also prevent mast cell de-granulation and histamine release.
EFFECTS OF FASTING ON DIGESTION
The Gut Circadian Rhythm is most active between 10am to 4pm. That’s usually the times I suggest to eat when recommending intermittent fasting. The biggest meal should be around lunch time because this is where the gut hormones (incretins such as GLP-1 and CCK) are the most active. If you eat a big meal later at night at traditional dinner times, you will release gut hormones at a time when they are not really that active, and you may end up with a deficiency in these hormones when you do need them most.
High histamine levels are associated with increased gut permeability (leaky gut) and food intolerances. We’ve just mentioned how fasting can reduce histamine levels and can thus deduce it will benefit those with gut problems significantly. Apart from reduced histamine, fasting or intermittent fasting will also rest the digestive system. This ‘resting’ phase is very important for the Migrating Motor Complex (MMC) to function properly. The MMC is waves of electrical activity that move through the intestines in a regular cycle, moving bacteria and debris from the small intestine down to the large intestine in between meals or during fasting. This MMC does not work when you are eating, so if you graze all day long you loose the ability to clear toxins from the small intestine effectively and increase the risk of developing conditions such as SIBO (Small Intestinal Bacterial Overgrowth).
EFFECTS OF FASTING ON METABOLIC HEALTH
The circadian rhythm is very much regulated by light. The master clock (circadian rhythm) in your brain gets the signal in the evening when it is dark that you are done for the day. But if you are eating then the peripheral clock in your liver will register that it is getting energy and wake up. When these two clocks are out of sync it leads to metabolic dysregulation.
As soon as you start to eat or drink something other than water, the brain starts the clock. Keeping all the eating and drinking within 12 hours of when that clock starts seems to be very important for metabolic health.
This means if you start breakfast at 6am and still have a wine at around 10pm you have extended that clock to 16 hours which is not going to be good for your overall health. Long term it will impact on your ability to lose weight and increase your risk of associated conditions such as PCOS, diabetes, cancer, heart disease, fatty liver, metabolic syndrome, etc.
But does this mean you can skip breakfast and lunch, and then have a big dinner later at night? Dr. Ruth Patterson doesn’t seem to think so and you can watch her interview below.
EFFECTS OF FASTING ON BREAST CANCER
Many growth factors such as estrogen, insulin, IGF-1 and others have been linked to obesity and cancer. This study was done – Prolonged Nightly Fasting and Breast Cancer Prognosis – that illustrated the timing of the meals had more importance than the content of the meals. Having a 13 hour fast reduced breast cancer risk by up to 40% and mortality by about 20% in this study.
You can watch this great interview with Dr. Ruth Patterson, Ph.D. on time-restricted eating in humans and breast cancer prevention.
There are so many more benefits to fasting and calorie restriction that we really could go on-and-on, and more papers are continuously being published on the subject. This just provides a quick high-light and brings back home the emphasis that we just eat too much, and it’s not doing our bodies, hormones, genes, and longevity prospects any good.
TAKE HOME MESSAGE
- Aim for 13+ hours of overnight fasting.
- Don’t eat or drink (anything else than water) later than 8pm but preferably stop around 6 or 7pm.
- If you are not hungry in the morning for breakfast then you are consuming calories too late at night.
- Considering following a ketogenic or similar diet by increasing your fats and decreasing your sugar or refined carbohydrate intake.
Correlation between serum gastrin concentration and rat stomach histidine decarboxylase activity
Leptin levels decline steadily during prolonged fasting in lean children
Effects of leptin on secretion of LH and FSH from primary cultured female rat pituitary cells
Energy intake, meal frequency, and health: a neurobiological perspective
Gut-derived serotonin is a multifunctional determinant to fasting adaptation
Obese gene expression: reduction by fasting and stimulation by insulin and glucose in lean mice, and persistent elevation in acquired (diet-induced) and genetic (yellow agouti) obesity
Effects of prolonged fasting on AMPK signaling, gene expression, and mitochondrial respiratory chain content in skeletal muscle from lean and obese individuals
Effects of fasting on plasma catecholamine, corticosterone and glucose concentrations under basal and stress conditions in individual rats
Catecholamine responses to hypocaloric diets and fasting in obese human subjects
Insulin, glucagon, and catecholamines in prevention of hypoglycemia during fasting