Note: This is an excerpt from: “The Complete Guide to Fasting: Heal Your Body Through Intermittent, Alternate-Day, and Extended Fasting.” by Dr. Jason Fung and Jimmy Moore. Please read that excellent guide for a clear and detailed understanding. This book has a lot of science backed studies, journals, tests and numerous references at the end of every chapter. This guide is the best reference instead of searching on the internet which gives a bunch of varying opinions most of them are not backed by science.
Some Busted Myths of Fasting:
Although fasting was widely practiced historically, most of us today grew up believing some fundamental myths about the dangers of fasting. They are repeated so often that they are often perceived as infallible truths. Some of the more common myths include:
- Fasting puts you in “starvation mode”
- Fasting makes you burn muscle
- Fasting causes low blood sugar
- Fasting results in overeating
- Fasting deprives the body of nutrients
- “It’s just crazy”
Although they were long ago disproven, these myths still persist. Most people mistakenly believe fasting is detrimental to health. The truth is quite the opposite—there are a significant number of health benefits.
Key Benefits of Fasting
Though the most obvious benefits of fasting are that it helps with weight loss and type 2 diabetes, but there are many other benefits, including autophagy (a cellular cleansing process), lipolysis (fat-burning), anti-aging effects (with increased HGH), and neurological benefits (BDNF). In other words, fasting can benefit your brain and help your body stay younger.
- Improves mental clarity and concentration
- Induces weight and body fat loss
- Lowers blood sugar levels
- Improves insulin sensitivity
- Increases energy
- Improves fat-burning
- Lowers blood cholesterol
- Prevents Alzheimer’s disease
- Extends life
- Reverses aging process
- Decreases inflammation (Detoxification)
Apart from the above health benefits, fasting is:
- You can feast after the fast (Enjoying the little pleasures of life)
- Works with any diet 😉
- Free (unless you buy water 😉 )
Here are some key explanation that illustrates the above benefits in detail. But please refer the book for more details with numerous supporting science backed references.
What Happens When We Eat?
Energy needed for the body is consumed and excess energy is stored as glycogen reserves (long chains of glucose molecules) and fat (lipogenesis) primarily by the key hormone insulin. Carbs and protein stimulate more insulin than fats.
What Happens When We Fast?
Insulin levels drop, signaling the body to start burning stored energy first from glycogen and then from stored body fat. The body transforms from fed state (high-insulin) to fast state (low-insulin) in the following phases (according to George Cahill, one of the leading experts in fasting physiology):
1. Feeding: Blood sugar levels rise as we absorb the incoming food, and insulin levels rise in response to move glucose into cells, which use it for energy. Excess glucose is stored as glycogen in the liver or converted to fat.
2. The postabsorptive phase (six to twenty-four hours after beginning fasting): At this point, blood sugar and insulin levels begin to fall. To supply energy, the liver starts to break down glycogen, releasing glucose. Glycogen stores last for approximately twenty-four to thirty-six hours.
3. Gluconeogenesis (twenty-four hours to two days after beginning fasting): At this point, glycogen stores have run out. The liver manufactures new glucose from amino acids in a process called gluconeogenesis (literally, “making new glucose”). In nondiabetic persons, glucose levels fall but stay within the normal range.
4. Ketosis (two to three days after beginning fasting): Low insulin levels stimulate lipolysis, the breakdown of fat for energy. Triglycerides, the form of fat used for storage, are broken into the glycerol backbone and three fatty acid chains. The glycerol is used for gluconeogenesis, so the amino acids formerly used can be reserved for protein synthesis. The fatty acids are used directly for energy by most tissues of the body, though not the brain. The body uses fatty acids to produce ketone bodies, which are capable of crossing the blood-brain barrier and are used by the brain for energy. After four days of fasting, approximately 75 percent of the energy used by the brain is provided by ketones. The two major types of ketones produced are beta-hydroxybutyrate and acetoacetate, which can increase over seventy fold during fasting.
5. The protein conservation phase (five days after beginning fasting): High levels of growth hormone maintain muscle mass and lean tissues. The energy for basic metabolism is almost entirely supplied by fatty acids and ketones. Blood glucose is maintained by gluconeogenesis using glycerol. Increased norepinephrine (adrenaline) levels prevent any decrease in metabolic rate. There is a normal amount of protein turnover, but it is not being used for energy.
Insulin Goes Down:
As the body becomes more sensitive to insulin, the following diseases that are directly linked to insulin resistance will be prevented and cured to the greater extent:
- Heart disease
- Alzheimer’s disease
- Type 2 diabetes
- High cholesterol
- High blood pressure
- Abdominal obesity
- Polycystic ovary syndrome
- Nonalcoholic steatohepatitis (fatty liver disease)
- Gastroesophageal reflux disease
- Obstructive sleep apnea
Electrolytes Remain Stable
Prolonged studies of fasting have found no evidence of electrolyte imbalances—the body has mechanisms in place to keep electrolytes stable during fasting.
Sodium and chloride: Daily salt requirements are quite low, and most of us exceed this by many orders of magnitude. During short-term fasts, salt depletion is not a concern. During prolonged fasting (more than one week), the kidneys are able to reabsorb and retain most of the salt needed by the body. However, rarely, some salt supplementation may be required.
Potassium, calcium, magnesium, and phosphorus: Potassium levels may decrease slightly during fasting, but they’ll remain in the normal range. Magnesium, calcium, and phosphorus levels are also stable during fasting. The bones carry large stores of these minerals—99 percent of what’s in the human body. Normally some minerals are lost in the stool and urine, but during fasting, that loss is minimized. However, in children and pregnant and breastfeeding women there is an ongoing demand for these minerals, so fasting is not advisable.”
Other vitamins and minerals: In a study of supervised fasts with only water and vitamins lasted up to 117 days, researchers confirmed that there were no changes in serum electrolytes, lipids, proteins, or amino acids. Moreover, they found that hunger was virtually absent during these prolonged fasts. So it advised to continue using daily multivitamin supplements.
Adrenaline Increases and Metabolism Speeds Up: The vast majority of people felt more energized and revitalized during fasting. This is because partly from fat-burning. But it’s also because adrenaline is used to release stored glycogen and to facilitate fat-burning, even if blood sugar is high. The increased adrenaline levels invigorates and stimulates the metabolism. In fact, studies show that after a four-day fast, resting energy expenditure increased by 12 percent.
Human Growth Hormone (HGH) Goes Up:
HGH is made by the pituitary gland. It plays a huge role in the normal development. It gradually decrease with age. Excessively low growth hormone levels in adults leads to more body fat, less muscle mass, and decreased bone density (osteopenia). Growth hormone also increases the availability of fats for fuel by raising levels of key enzymes, such as lipoprotein lipase and hepatic lipase. Since burning fat reduces the need for glucose, this helps maintain stable blood sugar. Many of the effects of aging may result from low growth hormone levels. Overeating suppresses growth hormone levels by as much as 80 percent. The most potent natural stimulus to growth hormone secretion is fasting.
In one study, over a five-day fasting period, growth hormone secretion more than doubled. During fasting, in addition to the usual early-morning spike of growth hormone (pulsatile), there is also regular secretion throughout the day (non-pulsatile). Both pulsatile and non-pulsatile release of growth hormone is increased during fasting. Interestingly, very low-calorie diets are not able to provoke the same growth hormone response.
A study of a religious forty-day fast found that baseline growth hormone levels increased from 0.73 ng/mL to peak at 9.86 ng/mL. That is a 1250 percent increase in growth hormone, all done without drugs. And a 1992 study showed a fivefold increase in growth hormone in response to a two-day fast.
Boosting the Brain Power
Animal studies show that fasting has remarkable promise as a therapeutic tool. Aging rats started on intermittent fasting regimens markedly improved their motor coordination, cognition, learning, and memory. Less age-related deterioration of neurons and fewer symptoms of Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. Interestingly, there was even increased brain connectivity and new neuron growth from stem cells. A protein called brain-derived neurotrophic factor (BDNF), which supports the growth of neurons and is important for long-term memory, is believed to be responsible for some of these benefits.
In addition, insulin levels have an inverse correlation to memory—that is, the lower the insulin level, the more memory improves. On the flip side, a higher body mass index is linked to decline in mental abilities and decreased blood flow to those areas of the brain involved in attention, focus, reasoning, and more complex, abstract thought. So fasting provides neurological benefits two ways: it decreases insulin and leads to consistent, maintained weight loss.
Significant research indicating a dramatic drop in inflammation, improvements in insulin signaling, and a near total “reset” of immune function with extended fasting. Abnormal and or pre-cancerous cells appear to be pushed towards apoptosis, which essentially selects for healthy cell types. When just some cellular components need to be replaced a process called autophagy kicks-in which helps reversing many of the signs and symptoms of aging while reducing the processes that appear to be at play in autoimmunity and cancer.
Increased levels of glucose, insulin, and proteins all turn off autophagy. And it doesn’t take much. Even as little as 3 grams of the amino acid leucine can stop autophagy. Here’s how it works: The mammalian target of rapamycin (mTOR) pathway is an important sensor of nutrient availability. When we eat carbohydrates or protein, insulin is secreted, and the increased insulin levels, or even just the amino acids from the breakdown of ingested protein, activate the mTOR pathway. The body senses that food is available and decides that since there’s plenty of energy to go around, there’s no need to eliminate the old subcellular machinery. The end result is the suppression of autophagy. In other words, the constant intake of food, such as snacking throughout the day, suppresses autophagy.
Lowers Blood Cholesterol
While fasting, as the dietary carbohydrates decline, the liver decreases its synthesis of triglycerides—since excess carbohydrates are converted to triglycerides, the absence of carbohydrates means fewer triglycerides. Triglycerides are released from the liver as VLDL, which is the precursor of LDL. Therefore, reduced VLDL eventually results in lowered LDL.
Who Should NOT Fast
Fasting isn’t for everyone. It carries certain risks and normal amounts of vitamins, minerals, and other essential nutrients are not ingested. Some people absolutely should not attempt therapeutic fasting, including:
- Those who are severely malnourished or underweight
- Children under eighteen years of age
- Pregnant women
- Breastfeeding women
Others should be cautious when fasting but don’t necessarily need to avoid it. In the following situations, it is wise to seek the advice of a health-care professional before attempting therapeutic fasting if you have:
- Some medication to take on regular basis.
- Type 1 or Type 2 Diabetes
- Gastroesophageal Reflux Disease
Breaking Your Fast
Breaking fast is very very important! Break your fast gently. The longer the fasting period, the gentler you must be. There is a natural tendency to overeat as soon as the fast is over—though, interestingly, most people say that this isn’t because of overwhelming hunger but more of a psychological need to eat. Overeating right after fasting often leads to stomach discomfort. While not serious, it can be quite uncomfortable. This problem tends to be self-correcting.
Try breaking your fast with a snack or small dish to start, then wait for thirty to sixty minutes before eating your main meal. This will usually give time for any waves of hunger to pass and allow you to gradually adjust to eating again. Short-duration fasts (twenty-four hours or less) generally require no special precautions, but for longer fasts, it is a good idea to plan ahead. Prepare a small dish and leave it in the refrigerator so that when it comes time to break the fast, you are ready and less likely to be tempted by the myriad of other convenience foods available
Tips for Breaking Your Fast with a Snack
• Make sure your portion sizes are small. You will be eating a full meal shortly, so there is no need to gorge
• Take the time to chew thoroughly. This will greatly help your digestive system, which has been resting for a while. You are slowly bringing your system back online.
• Take your time in general. Your fast is over. If you are feeling anxious to eat again, take comfort knowing you will be having a whole meal within the hour.
• Don’t forget to drink water! Drink a tall glass of water before you break your fast and after your first meal. People often forget to consume fluid once they stop fasting, but we often mistake thirst for hunger. Make sure you are staying hydrated so you don’t overeat.
I don’t want to copy all the book here 🙂 . The motive behind this post is to motivate you towards water fasting by giving a few illustrations from the guide. I hope this would help to avoid a lot of paranoid about fasting especially extended fasting. Please buy and read the book if you want to reap the benefits. The guide explains how to fast, when to stop which, is very very important before you start the fasting. Some tips to overcome minor caveats while fasting.. and so on. Wishing you all the best 👍
I would suggest to start with intermittent fasting if you haven’t fast earlier.
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