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Intermittent Fasting 101 | Schedules and Health Benefits

How great would it be to lose weight, feel younger, and get healthier and live longer without eating less or exercising?

The closest you will get is intermittent fasting.

Intermittent fasting involves eating in a short window of time and fasting the rest of the time. 

What is Intermittent Fasting_ The Ultimate Beginner's Guide.-min

In this article, I share the science behind intermittent fasting and explain it in simple terms. You will learn the intermittent fasting times, benefits, and mistakes to avoid.

I started intermittent fasting two years ago and I’ve experienced the benefits and learned from the mistakes.

The first week of intermittent fasting is tough, but the benefits are unparalleled. The good news is the weakness and hunger go away and habits can be changed.

Keep reading to learn about the benefits, tips, and what to avoid.


Table of Contents


What is Intermittent Fasting?

Intermittent fasting involves eating in a short window of time and fasting the rest of the time. You don’t have to restrict the kind of food or the amount that you eat for the benefits.

Intermittent fasting is very popular in the health and fitness community right now. This is a good thing, but it is more than a fad.

Fasting has been practiced throughout history during times of famine. Food was not always available like it is now. With food available 24 hours a day, intermittent fasting is more important than ever.

There are many reasons for fasting. For instance, several religions practice fasting.

In this article, we will focus on the health benefits of intermittent fasting.

Intermittent fasting involves eating in a short window of time and fasting the rest of the time. You do not have to restrict the kind of food or the amount that you eat to get the benefitsClick to Tweet

A chart with left side pink, right side blue, 5 Most Popular Intermittent fasting schedules

Intermittent Fasting Guide and Schedules

These are the most common intermittent fasting methods. They offer similar benefits, but some are easier than others. Find the method that works for you.

The 16/8 Fasting Method

The 16/8 fasting method, also known as the Leangains method, involves skipping breakfast and eating within a period of up to 8 hours and fasting for 16 hours. For many, this is the easiest fasting method.

Start your fast after dinner and wait at least 12 hours before you eat breakfast the next day. Your body needs about four hours to digest and after that, your liver needs about eight hours to cleanse (1).

Eventually, extend your daily fast up to 16 hours and eat within an 8-hour window. Also, give your body at least 3 hours between meals in your eating window.

For example, you would eat between noon and 8 PM, and fast from 8 PM until noon the next day.


The 20:4 Fasting Method

The 20:4 fasting method means eating within a 4-hour eating window followed by a 20-hour fast. Start your fast after dinner and wait 20 hours until you eat again. Then, eat within a 4-hour window, one or two meals with 3 hours in between.

For example, eat between 2 PM and 6 PM, either one or to meals, then fast until 2 PM the next day.

For the best results, wait at least three hours between meals or eat one large meal a day.


Dr. Nun Amen Ra: Vegan Strong man Eats One Meal A Day

Watch this video of Dr. Nun S. Amen Ra to see how it is possible to eat one meal a day.



The 5:2 Fasting Diet

This method involves eating normally for five days of the week. On two non-consecutive days, you consume about 500 calories

The 24-Hour Fast

With the 24-hour fast or the eat-stop-eat fasting method, you fast for 24 hours once or twice a week. This method involves fasting from lunch on day 1 until lunch on day 2. You still eat every day, but only once during that day.

The best way to do this method is to fast after dinner and not eat until dinner the next day.


The 36-Hour Fast

This fast involves fasting for an entire day and night, about 36 hours altogether. For example, fast after dinner on day one, fast during day 2, and break your fast on day 3.


Extended Fasting Risks

Dr. Jason Fung recommends a general multivitamin for fasts longer than 48 hours and discourages anyone from fasting longer than 14 days due to the risk of re-feeding syndrome. Re-feeding syndrome is the potentially fatal changes in fluids and electrolytes that may occur in feeding malnourished people (2).


The Most Popular Fasting Method

The 16/8 Fasting Method is my favorite method and it is the most popular. This method is easier due to its habit-building potential. Your body becomes used to it and you don’t even have to think about it.

In my opinion, the 5:2 Diet is the least beneficial. The benefits of a fast come from giving your body a chance to cleanse not the restriction of calories.

There are several different fasting plans that share the same benefits. Choose a fasting method that works for you. And remember that it gets easier the longer you stay with it

A picture of a fit woman from behind, headline 12 Intermittent Fasting Benefits


Intermittent Fasting Benefits

When you start a fast, your body undergoes many beneficial biological processes. This is the time when your body heals, cleanses, and repairs itself.


1. Intermittent Fasting Initiates Autophagy

When you eat, your body goes into an anabolic state in which you store both nutrients and toxins. Eating is vital for building cells and storing nutrients for times of scarcity. Anabolism is activated by the hormone insulin.

Fasting for over 6 hours your body releases human growth hormone (HGH) which activates catabolism or autophagy.

Autophagy is a Greek word, auto meaning “self” and phagy meaning “to eat”. It literally means to eat oneself. When your body determines that there isn’t enough food to eat it starts searching your cells for anything you don’t need.

Your body recycles damaged or useless cells into fuel or building materials to renew your cells (3). You eliminate useless or harmful junk and gain new healthy cells. Thereby your body stays young and healthy.

Learn more about the power of autophagy in this interesting video from Dr. Boz [Annette Bosworth, MD]


2. Fasting Boosts Human Growth Hormone

Human Growth Hormone (HG) is a small protein produced by the pituitary gland and released into the bloodstream (4). HGH is released in bursts, as levels rise following exercise, trauma, and sleep.

Besides activating autophagy, HGH initiates changes in metabolism that promote fat burning, saving proteins and building muscle (5, 6).

These proteins and amino acids are used to enhance brain and neuron processing. They also rebuild collagen which improves the strength and function of bones, muscles, ligaments, and tendons.

Further, HGH supports the skin, reduces wrinkles, and heals cuts and burns faster (7, 8, 9, 10).

Researchers at the Intermountain Medical Center Heart Institute discovered that men who fasted for 24 hours had a 2,000% increase in blood levels of HGH (11). Women also had a 1300% increase in HGH.

10 Best Vegan Protein Sources For Weight Loss and Muscle


3. Intermittent Fasting Reduces Insulin Resistance

Intermittent fasting may lower blood sugar, reduce insulin resistance, and prevent type 2 diabetes.

Insulin, a hormone produced by your pancreas, unlocks your cells. This lets the sugar from the food you eat enter your cells to be used as energy (13). Generally, those with type 2 diabetes have a combination of insulin resistance and high blood sugar.


Insulin Versus HGH

Insulin and HGH have opposite functions. HGH supports tissue repair, efficient energy usage, and anti-inflammatory immune function (14). Insulin is focused on energy storage, cell division, and pro-inflammatory immune activity (15).

Insulin and HGH cannot function at the same time. Because insulin is dominant, HGH is inhibited when conditions demand insulin (16, 17). For example, when you eat carbohydrates your body releases insulin. If you are always in a fed state your HGH levels remain low.


Insulin resistance and Fasting

Insulin resistance happens when your cells become unresponsive to insulin. Your cells do not get unlocked to let enough sugar (glucose) enter your cells. As a result, blood sugar levels remain elevated and your cells are starved of glucose.

Fortunately, intermittent fasting has shown to both lower insulin resistance and blood sugar levels (18).

Studies have shown that intermittent fasting can reduce fasting blood sugar levels by 3-6%, and reduce fasting insulin levels by 20-31% (18).

Further, one study of diabetic rats found that intermittent fasting protects against kidney damage, a serious problem related to diabetes (19).

One study, however, found that a 22-day long intermittent fasting schedule worsened blood sugar levels for women (20).


4. Intermittent Fasting Can Ease Inflammation

Oxidative stress comes from an unfavorable balance of free radicals and antioxidants. Free radicals are highly reactive and unstable molecules that are produced when oxygen loses an electron (21). Free radicals can damage (22) biologically vital molecules such as DNA, proteins, lipids, and carbohydrates.

Oxidative stress is (22) one of the major factors of aging and most chronic diseases including:

  • cancer
  • cardiovascular disease
  • Alzheimer’s Disease
  • diabetes
  • Parkinson’s disease
  • macular degeneration

Several studies show Intermittent fasting may help your body reduce oxidative damage and improve your cell’s stress resistance (2324).

Other studies find that intermittent fasting can reduce inflammation (242526). Inflammation is one of your body’s healing mechanisms, but chronic inflammation promotes chronic diseases and aging.

Related Post: What Are Free Radicals and How Can We Fight Them?


5. Intermittent Fasting May Be Good For Your Heart

Heart disease is currently the leading cause of death in the world (27).

Intermittent fasting may reduce the risk of heart disease by improving the biomarkers of health. These biomarkers include visceral fat,  body weight, cholesterol levels, insulin sensitivity, vascular function, blood pressure, and blood lipid levels (182829).

Related Post: What is a Good Resting Heart Rate for My Age? Resting Heart Rate Chart


6. Intermittent Fasting Promotes Weight Loss

The most popular reason for trying intermittent fasting is for weight loss (30).

How does intermittent fasting help you lose weight?

One way people lose weight with intermittent fasting is by eating fewer meals and fewer calories. But you don’t need to cut your calories to get the benefits of intermittent fasting.

Learn more about how to get the benefits of caloric restriction without eating less in How to Slow Down Aging mTor is Key

More importantly, intermittent fasting promotes the right hormones for weight loss. It lowers insulin levels and promotes higher HGH and norepinephrine. All of which helps convert body fat into energy.

Thereby, fasting increases your metabolic rate by 3.6-14%, which helps you burn more calories (31, 32).

You can eat the same amount of food and burn more calories. Or you can eat fewer calories and still have a higher metabolism. You may lose more weight by eating fewer calories, but it is not necessary.


How much weight can you lose with intermittent fasting?

A 2014 review of scientific studies found that intermittent fasting can cause weight loss of 3-8% over a period of 3 to 24 weeks  (32). For a person weighing 150 pounds, that means about 4.5 to 12 pounds over 3 to 24 weeks. The amount, however, varies from person to person.

The same people in the review lost about 4-7% of their waist circumference. This means that they lost plenty of belly fat or visceral fat. Visceral fat stores around your abdominal organs and is a major risk factor for serious diseases such as heart disease, cancer, and dementia (33).

Your body stores toxins, or what it doesn’t know what to do with, in your fat cells. If intermittent fasting allows your body to eliminate and recycle wastes more efficiently, then theoretically you will store less fat in the first place.


7. Intermittent Fasting Promotes Healing and Immunity

Intermittent fasting promotes healing and boosts immunity (34, 35, 36).

Have you ever wondered why you feel nauseous when you have an infection? This is your body’s natural mechanism of getting you to stop eating. Fasting allows your body to focus on healing and killing pathogens.

Give your body the time it needs to heal by restricting your eating to a short window of time.


8. Intermittent Fasting May Prevent Cancer

Cancer is a name given to over a hundred dreaded diseases in which abnormal cells grow out of control and cause tissue damage. Cancer develops when old cells fail to die and form abnormal cells (37). Autophagy, when your body recycles damaged cells, may help prevent cancer.

There are multiple animal studies that show promising evidence that intermittent fasting may help prevent cancer (38394041). But more studies need to be performed on humans.

Lastly, one study found that short fasting may reduce the side effects of cancer treatments (42).


9. Intermittent Fasting Improves Brain Function

All the same benefits of intermittent fasting such as reducing inflammation, lowering blood sugar, and lowering insulin resistance also promote brain health.

Studies have shown that the interruption of neuronal autophagy increases your risk of neurodegenerative diseases (43). In other words, if your brain does not consistently reach a fasted state long enough to cleanse itself it could increase your chances of developing a brain disorder or cause mental decline.

Consequently, high levels of circulating insulin prevent neuronal autophagy thereby causing accelerated neurodegenerative states, or faster brain aging (44).

The good news is that Intermittent fasting gives your brain a chance to cleanse itself and grow new neurons and connections for optimal function (45). Therefore, with less waste, your brain can heal and grow faster and be more efficient.

Did you know that your brain uses up to 50% of your energy?

Intermittent fasting raises levels of the hormone brain-derived neurotrophic factor (BDNF) (46, 47, 48). A deficiency of BDNF is a possible factor in depression and other brain problems (49).


Animal studies on intermittent fasting and brain function

  • Studies of rats have found that intermittent fasting may promote the growth of new nerve cells, which should improve brain function (50, 51).
  • Other animal studies have found that intermittent fasting protects against brain damage from strokes (52).


10. Intermittent Fasting May Prevent Alzheimer’s Disease

Alzheimer’s disease is the most common form of dementia and affects memory, thinking, and behavior (52). Symptoms develop gradually but worsen over time. Until eventually, it disrupts simple everyday tasks. Alzheimer’s disease has no known cure making prevention vital.

Your brain has about 100 billion nerve cells. Every nerve cell is connected to a group of other cells to form a communication network (53). Each group of nerve cells has a specific job such as learning, thinking, and remembering.

Plaques and tangles are believed to be the primary cause of nerve cell damage and death (53).

  • Plaques are deposits of protein fragments that accumulate in the spaces between nerve cells.
  • Tangles are twisted protein fibers that build up inside nerve cells.

Autophagy, which eliminates and recycles waste, may help eliminate the plaques and tangles that damage nerve cells.


BDNF and Nerve Cells

Brain-derived Neurotrophic Factor (BDNF) levels control the creation of new nerve cells and synapses and communication networks within the brain. Further, higher levels of BDNF promote healthier nerve cells and stronger communication systems between nerve cells (54).

At the other extreme, low levels of BDNF are associated with Alzheimer’s, dementia, memory loss, and other brain functioning problems (55).

Intermittent fasting from 16-18 hours has shown to significantly boost BDNF levels (56).


Animal Studies on Intermittent Fasting and Alzheimer’s Disease

  • One study of rats found that intermittent fasting may delay Alzheimer’s disease or minimize its symptoms (57).
  • Other animal studies show that intermittent fasting may help prevent other neurodegenerative diseases such as Parkinson’s and Huntington’s disease (5658).


11. Intermittent Fasting Promotes Longevity

Intermittent fasting may be one of the easiest ways to add more quality years to your life.


Animal Studies On Fasting And Longevity

  • Studies of rats have found that intermittent fasting increases lifespan similar to caloric restriction (59, 60).
  • In one study, rats that fasted every other day lived 83% longer than rats that ate regularly (61).

Although more studies need to be done on humans, intermittent fasting looks promising for increasing lifespan.


12. Intermittent Fasting Improves Energy Efficiency

Your body needs “good” stress like fasting to adapt and survive.

Exercise and food scarcity force your body to become more efficient. Thereby you adapt more effectively to your environment.

The problem is that technology has made it easier to avoid exercise and food scarcity. Depending on where you live, food is never far away.

Interestingly, fasting may give your brain cells the same mild stress that exercise exerts on your muscle cells. This mild stress forces your cells to adapt and become more energy-efficient (62).

Who Should Not Fast and Why?

You should not practice intermittent fasting if you are (63):

  • Underweight – further fat loss would not be beneficial
  • Pregnant or nursing – you need the extra nutrition for your child
  • Children under 18 – children need extra nutrition for growth and development


Who should Fast Under Supervision (63)

  • If you are taking prescription medication
  • If you have type 1 or type 2 diabetes
  • If you have “gout or high uric acid”


Intermittent Fasting Mistakes to Avoid

1. Not eating enough calories

For the most part, eat the same amount of calories as you normally would. The symptoms of caloric restriction include (64) very low blood pressure, loss of libido, infertility, menstrual irregularities, bone loss, cold sensitivity, loss of strength, slow healing, depression, and irritability.


2. Not Eating Enough Nutrients

You should focus on eating nutrient-rich foods in your short eating window to prevent deficiencies. Intermittent fasting alone is not enough to get all the benefits. Give your body what it needs to build a new and healthy body.


3. Fasting and Overeating

Don’t use your eating window to binge on junk food or foods low in nutrition. Think of the opportunity cost of everything you eat. Will it bring you closer to your health goals?


4. Not Drinking Enough Water

Water helps you clear out all the wastes from the cleansing process of fasting. You should drink at least one ounce of water for every pound of body weight. You need even more water when you exercise or live in a dry environment.

How Much Water Should I Drink a Day in Ounces?


5. Not Choosing a Fasting Plan That Works For You

Everyone is different, find a plan that works for you. If a fasting plan is causing more problems then try something else.


6. Obsessing With Arbitrary Fasting Times

A consistent schedule makes intermittent fasting easier. But don’t be a slave to arbitrary times. Sometimes your body will need to refuel sooner or extend its cleansing process.

Eat when your body feels ready. If you are not hungry your body may need more time to digest and cleanse. But if you are hungry sooner, you may be deficient.


High-Intensity Interval Training and Fasting

Many people believe that doing high-Intensity Interval Training (HIIT) in a fasted state is the perfect workout for weight loss. But this is an extreme method. It isn’t necessary to get the benefits of intermittent fasting.

HIIT is an effective workout on its own, so I included it in this article. Do not exercise in a fasted state until your body has time to adapt to the change.


What is High-Intensity Interval Training?

  • High-Intensity Interval Training is a training method where you give 100% effort in a quick, intense burst of exercise, then resting.
  • HIIT is as simple as doing one exercise, like sprinting, as fast as you safely can for 30 seconds, then resting for 90 seconds.
  • Make sure to warm up first and start with one rep when starting out.
  • Rest for several days in between HIIT days. Build up slowly to a workout of several reps that only takes about 15 minutes.
  • For the best results, don’t set an arbitrary time. Instead, push to your max.
  • Rest and recover until you are ready to give 100% again.

Learn more about how to do HIIT the right way and its benefits in this short video.


Intermittent Fasting Quotes

“He who eats until he is sick must fast until he is well.”∼English Proverb


“When the stomach is full, it is easy to talk of fasting.” ∼St. Jerome


“I assert that fasting is the most efficient means for correcting any disease.”

∼Adolph Mayer, M.D., Fast Cures – Wondercures


“If thou wouldst preserve a sound body, use fasting and walking; if a healthful soul, fasting and praying; walking exercises the body, praying exercises the soul, fasting cleanses both.”

∼Francis Quarles


“Periodic fasting can help clear up the mind and strengthen the body and the spirit.” ∼Ezra Taft Benson


“Fasting is the first principle of medicine; fast and see the strength of the spirit reveal itself.”



“The light of the world will illuminate within you when you fast and purify yourself.”

∼Mahatma Gandhi


“Every fool can fast, but only the wise man knows how to break a fast.” ∼G.B. Shaw


“The observances of the church concerning feasts and fasts are tolerably well-kept, since the rich keep the feasts and the poor keep the fasts.”

∼Sydney Smith


“Fasting is the greatest remedy – the physician within.” ∼Philippus Paracelsus


“Fasting today makes the food good tomorrow.” ∼German Proverb


“A fast is better than a bad meal.”∼Irish Proverb


“The very act of eating can be exhausting; it takes a lot of energy to digest food. When the body is freed from that chore, it naturally feels lighter and much more vibrant.”

∼Allan Cott


“(W)hen the faculties are empty, then your whole being listens.” ∼Thomas Merton


“Fasting cures diseases, dries up bodily humors, puts demons to flight, gets rid of impure thoughts, makes the mind clearer and the heart purer, the body sanctified, and raises man to the throne of God.”

∼Athenaeus of Naucratis


“To lengthen thy life, lessen thy meals.” ∼Benjamin Franklin


“Fasting of the body is food for the soul.”∼John Chrysostom

Intermittent Fasting Books

The Scientific Approach to Intermittent Fasting by Dr. Michael Vanderschelden is an easy to understand resource on fasting. He explains the science behind fasting and provides actionable plans, steps, and motivation to give it a try.

One thing that stands out about this book is that Dr. Vanderschelden shares how to implement exercise and fasting together. Click here to check the price on Amazon.


Heal Yourself 101by Markus Rothkranz is a step-by-step guide to overcoming almost any health problem. Not only will you learn about fasting, but you will also learn how your body can heal itself when you give your body and mind only what it needs to thrive. You don’t have to do everything in this book to get the benefits.

I started doing these steps one by one and within a few months of using some of the ideas in this book, I had more energy, my mind was clear, and I was pain-free!

Last time I checked, you can download his book for free!

For all my product recommendations, visit my secret weapon resources page.


Intermittent Fasting FAQ

Can you drink during intermittent fasting?

Generally, you can drink tea or coffee and remain in a fasted state if it has less than 50 calories. But if you want the best results, drink water during your fast.

How much weight can you lose in a month with intermittent fasting?

Studies show that intermittent fasting can help people lose 3-8% of their body weight over a period of 3 to 24 weeks. A month (about four weeks) would be closer to 3%, or 3 lbs for 100 lbs of body weight.

Is Intermittent Fasting Good For You?

Intermittent fasting is generally good for you and has many health benefits including the following: promotes weight loss, reduces insulin resistance, promotes heart health, prevents cancer, improves brain function, and increases longevity.

What Can I Eat During Intermittent Fasting?

Food is generally not allowed during the fasting window. Increase your fasting window slowly and eat plenty of high fiber foods and nutrient-dense foods during your eating window to suppress hunger longer.


What Is Your “Why” For Fasting?

Intermittent fasting is one of the simplest and most effective ways to improve your health. In this article, we covered the benefits of fasting and different methods, who should not fast and fasting mistakes to avoid.

The benefits of intermittent fasting include the initiation of autophagy, diabetes prevention, fat loss, energy, heart health, cancer prevention,  brain health and function, and increased longevity.

The cancer prevention benefits of intermittent fasting may prove to be one of the greatest health discoveries. I am not going to wait for all the benefits of fasting, or other healthy practices, to be proven before I make a positive change.

“He Who Has a Why to Live For Can Bear Almost Any How.” ∼ Friedrich Nietzsche

What is your “why” for fasting or making a positive change?


Sources Cited


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