LifeBox Nutrition

My Account

How to Fast: The Ultimate Guide for Beginners

Sep 08, 2016 | Austin Gill

New to Fasting? You're In the Right Place

I just completed a 5 day water fast, and video'd the experience - you can watch the VLOG here.

While discussing my fast with people after the fact (I don’t tell people I’m fasting while I’m fasting) I got some pretty wild responses.

Most people literally couldn’t wrap their minds around the fact that I didn’t eat for 5 days. I could see them struggling with whether or not they believed me.

Once they reconciled that I had actually fasted many people told me I was crazy or immediately said "that can’t be good for you" and set in on me with the 3 meals per day & not eating will damage your metabolism lecture.

There were a few open minded who set their disbelief aside for long enough to bombard me with questions. “Why did you do that? Actually, how did you do that?”.

In retrospect, I should have expected resistance and doubt and curiosity. Fasting is extreme, especially for people new to the practice - it was to me when I first started.

I've now been fasting mimicking once per month for the past 14 months (as of February 2017). I also intermittent fast, also known as time restricted feeding, so I only eat from 2:00p to 8:00p each day (18:6). I randomly throw in a single day fast when my body feels like it needs it, and I mentioned that I just completed a 5 day water fast. Edit: I've since completed my second pure water fast that lasted 7 days.

All this to say, I fast a lot. I'm fairly knowledgable on the subject, yet I was having trouble explaining it to people who were trying to wrap their mind around why a normal person would ever voluntarily give up food.

So I decided to write this, it's a summary of much of what I've learned about fasting written to act as a guide for anyone who may be interested in learning how to fast.

What is Fasting?

“The philosophy of fasting calls upon us to know ourselves, to master ourselves, and to discipline ourselves the better to free ourselves. To fast is to identify our dependencies, and free ourselves from them.” ~ Tariq Ramadan

Fasting is voluntary abstinence. You can fast from many things, but I'm going to focus on dietary fasting - fasting from food and drink, be it some or all or any combination in between.

Fasting is not starvation, despite popular belief. Starvation is when your body suffers damage from lack of energy and nutrients.

When you fast your body burns stored fat for energy; there is only risk of starvation when you don't have any fat to burn.

Most fasting experts agree that this risk begins at body fat percentages below 5% (think competitive bodybuilders). For the vast majority of us this isn’t even remotely a concern.

Fasting also refers to the physiological state of being “fasted”, as opposed to being "fed" where your body is busy digesting food.

How Long to Fast: The 3 Consecutive Day Rule

Attaining benefits beyond simple weight loss requires you reach and spend time in the fully fasted state. So let’s look at how that happens, then at why you want it to.

The Physiology of Fasting: An Overview

Your body has two basic metabolic states, or processes for producing energy - glycolysis and ketosis.

Glycolysis is your normal state where your body runs on energy from glucose (sugar) in your blood from the food you eat. Most people never leave this state.

When glucose isn’t available your body has the ability to use fat for energy - this is the metabolic state of ketosis. I know right, fat actually serves a purpose! Who knew.

The physiological process of transitioning from glycolysis (running on food) to ketosis (running on fat) happens in 4 stages.

  1. Absorptive State (up to 4 hours into fasting): You eat and your body raises insulin to transport the glucose in your blood stream to where it is needed, like your muscles and brain. Extra glucose is stored as glycogen.
  2. Postabsorptive State (6 to 24 hours into fasting): Also known as glycogenolysis, glucose in your bloodstream is low so your body begins to break down glycogen stores in your liver for energy.
  3. Gluconeogenesis (24 hours to 2 days into fasting): Glycogen stores have been depleted so your liver begins producing new glucose using amino acids and glycerol to stabilize your blood sugar.
  4. Ketosis (2 to 3 days into fasting): Your body begins breaking down fat to produce a type of energy known as ketone bodies to fuel your brain.

You need about 3 days to get into full fasting ketosis, then you want to spend a little time there - ala the 3 consecutive day rule.

Now on to the why.

Why Achieving Fasting Ketosis Matters

Our objective for fasting, in the most general sense, is to heal. More specifically to permanently heal. True healing results from the interplay of multiple very-complicated physiological processes. I’m only going to discuss two.

The first is autophagy. Think of autophagy as your body’s recycling program. It gets rid of old, worn out, malfunctioning parts (cells). Autophagy is good.

Second, fasting stimulates growth hormone production, which signals your body to make new healthy parts (stem cells) to replace the old ones that were thrown out.

Together these two processes produce a cascade of benefits such as reducing inflammation, boosting your immune system, improving your metabolic efficiency, and even lowering your risk of developing chronic disease and cancer.

Autophagy and growth hormone production are at their strongest in the fully fasted state, fasting ketosis.

[Note: If you're interested in reading more about these topics, I have included a list of my favorite resources at the bottom of this article.]

Why Fast: Understanding the Benefits to Get Motivated

Fasting is the single most beneficial thing you can do for your health. But knowing that fasting is good for you is one thing, putting it into practice is another entirely.

Before you fast, take a moment to consider why you're fasting - figuring out your why will give you the motivation to push through difficult times. Here's a few reasons to get you started . . .

Reason #1: To Improve Your Health - That sounds so boring, but it’s important. I already talked about autophagy and growth hormone production, here are some specific benefits you can expect from fasting.

  • More energy
  • Healthier, clearer skin
  • Healthier teeth and gums
  • Better quality sleep
  • A clean and healthy cardiovascular system (lower risk of cardiovascular disease)
  • A decrease in anxiety and tension
  • Dramatic reduction or complete elimination of aches and pains in muscles and joints
  • Decrease or elimination of headaches
  • Improve memory and problem solving
  • Stabilization of blood pressure
  • Stronger and more efficient digestion
  • Stabilization of bowel movements
  • Elimination of stored toxins
  • Improvement with a wide variety of chronic degenerative health conditions, including autoimmune disorders
  • Prevent disease and cancer
  • Reduce side effects of radiation and chemotherapy treatments
  • Increase longevity

Reason #2: To Lose Weight - There are many people who will tell you not to fast for weight loss. And while there may be extreme cases where it wouldn't be appropriate, for most people fasting is the most powerful weight loss tool at their disposal.

Fasting is the most effective and lasting method for weight loss. You'll lose weight, set your body up to maintain a healthy weight, and reap a plethora of other health benefits on the side - all very much unlike dieting, which has essentially no lasting health benefits.

If you don’t want to take my word for it, one well respected proponent of fasting for weight loss, specifically in the case of diabetics, is fasting expert Dr. Jason Fung, he writes extensively about it on his blog (one of my favorites). This is his post about fasting for weight loss.

Reason #3: For Fun - For fun? Sure! Fasting is a challenge, and many people see challenging themselves as fun. I do.

Fasting is also an excellent way to alleviate stress, to enlighten your spirit, to meditate, to strengthen your willpower, to exercise discipline, to learn about yourself, and to break addictions. All things that could be described as fun.

We have a philosophy here at LifeBox: Do hard things so that you can do hard things. You'll be better and stronger for it.

Reason #4: For Mindfulness - Fasting contrasts sharply with normality, your regular life patterns. It also presents you with seemingly endless amounts of time since you aren't eating, presenting an opportunity to turn your attention to other things.

I become increasingly aware of myself when I fast; I feel more open and in tune with the world around me, yet less affected by my environment.

I feel separated, but not isolated, giving me a greater sense of calm and a confidence in my own ability to control myself and how I allow outside influences to affect me.

Increasing my control over life, or more specifically myself makes me happy. I think it will you too.


Improve your health, break addiction, challenge yourself for fun, find a sense of calm, grow your inner strength. Once you have your reason you have your motivation. Now here’s what you do with it.

How to Fast


Never Fasted Before? Have No Fear

Mention of the word fasting sends fear and apprehension through many people, but it shouldn’t. The difficulty is blown way out of proportion.

Fasting is not uniquely difficult. It’s just like anything else you do for the first time, it’s hard because you've never done it before. It gets easier.

I already covered the 3 consecutive day rule, which is the ultimate goal. So as I go through the different forms of fasting here, I do so with the intention of using them to build up to an extended fast.

Each form, however, can be useful on its own.

But before I get to those, my first recommendation is just dive in! After you make it through the first two days your body adjusts and will provide you with energy. Many people even report being overcome with a feeling of euphoria.

If stringing 3 or 4 fasting days together sounds daunting to you, then here are some strategies you can use to build up that.

Steps for Building Up to an Extended Fast

Step 1: Intermittent Fasting (IF)

The idea is to eat within a specified time window. You already do this every day.

For example: let’s say you sleep from 10:00p to 6:00a, that’s 8 hours. Let’s also assume that you eat your first meal right when you wake up and your last meal right before you go to bed. So your IF schedule would be annotated as 8:16 - 8 hours fasting, 16 hours feasting.

Work towards transitioning more of your time into the fasted state.

Make a rule that you won’t eat after 8:00p; you are now at 10:14 IF. Then try pushing breakfast back until 8:00a, so now you're only eating from 8:00a until 8:00p making your IF Schedule 12:12.

Next try skipping breakfast! Make lunch at 12:00 your first meal of the day, an IF Schedule of 16:8. It may take a week to adjust, but before long your body won’t even be hungry until lunch time and you'll feel great in the mornings!

[I’ve been doing IF for the last year. My schedule is 18:6, so I only eat from 2:00p to 8:00p every day. I feel great and am never hungry in the mornings. I even work out fasted every day at 12:00, right before I eat. I love it.]

Step Two: Single Day Fast

Next try a single day fast, which won’t be any big deal now that you are already skipping breakfast every day.

Aim for a 24 Hour fast your first time.

For example: You finish dinner on Monday at 7:00p, skip breakfast and lunch on Tuesday, then eat dinner Tuesday night at 7:00p. You just fasted for 24 hours! Doesn’t sound so bad when you realize that it just means skipping two meals.

Next try a 36 hour fast, a true one day fast.

Example: You finish dinner on Monday at 7:00p, skip breakfast and lunch AND dinner on Tuesday, then eat breakfast Wednesday morning at 7:00a. Boom, you just did a full day fast. You’ll be surprised how easy it is, I promise.

Eat breakfast on Wednesday?? But I’ve been intermittent fasting and never eat breakfast. Well I’m glad you brought it up, just push your “break fast” meal back to your normal lunch time and you have a 42 hour fast!

Preparing for Your First Extended Fast

Now that you're comfortable with fasting and have a few single day fasts under your belt, you're ready to take on your first full 3 day fast (84 hours). Here’s how to get ready.

The Days Leading Up

Get Your Mind Right - We spoke about understanding the benefits and defining your own objectives. Make it personal by writing yours down and latch on to that motivation.

Because although fasting is simple, it's not easy. It's doable, but still a challenge. Know that, prepare for it, and get comfortable with it.

Adjust Your Expectations - Fasting is a powerful practice, but it’s not a quick fix. It's an intervention for the sake of spurring continual progress, it’s not a panacea.

Think of fasting as a step, albeit a large one, towards a sustainable healthy lifestyle.

Prepare Your Body - I recommend cleaning up your diet a few days to a week before your fast. Cut out sugar and carbohydrates; this will lower your blood sugar and ease the transition period.

Talk to Your Doctor - Your body and medical history are unique, go talk to your doctor just to see if there are any special precautions you should take. It’s always good to consult an expert, especially when it comes to your health.

Fasting Safety

Fasting is not dangerous. Can it be if used incorrectly or in the wrong situations? Yes, but a jelly bean can be dangerous if you stick it up your nose . . .

Anyway, safety is sexy. So here are a few things you can do to be sure you have all your bases covered.

Do Your Research - Like any worthwhile endeavor, you should do some reading and studying before you dive in. If you're reading this then you're already on the right track.

Take some extra time to get familiar with fasting in order to gain a better understanding of what to expect. (I’ve linked some sources at the bottom)

Rest - Many people will tell you to suspend all normal activities. I don’t think that's necessary.

Make sure to get a full night’s sleep, and be aware of how you feel. Listen to your body. If you get tired, take a nap!

I add an extra hour to my normal sleep schedule when fasting.

Get Some Sunlight - Sunlight exposure will greatly improve your experience. Sunlight contains essential vitamins and releases hormones in your body that boost your mood. And who doesn’t love getting some fresh air?

Stay Hydrated - To transition from the fed state to the fasted state your body must use up your glycogen stores. Glycogen holds a lot of water, so when it leaves a lot of water goes with it, which could cause dehydration.

There are many different opinions on how much water is enough, my rule is to drink when you're thirsty. An indicator that you are well hydrated is clear or a very pale yellow urine.


Special Considerations

Fasting with Diabetes - There are many cases where fasting has reversed Type II diabetes. It is a powerful practice and one well worth considering for anyone suffering from chronic diseases.

If you are diabetic (Type II), talk with your doctor. You may want to consider how to adjust your medication while fasting to account for lower glucose levels, among other things.

Now for the fun stuff.

Tips to Make Fasting More Enjoyable

Don’t Tell People You Are Fasting - Fasting is widely misunderstood. Most people who aren’t familiar or at least curious about alternative health lifestyles and natural healing practices won’t understand what you’re doing. They will most likely react negatively, disapproving and encouraging you to stop. I recommend just saving yourself the trouble and not telling people.

I do tell my family or close friends when I'm fasting. Be thoughtful in who you decide to tell, choose someone who will be receptive and supportive.

Dealing with Hunger - Before my first fast, I expected to feel like I was starving the whole time. That wasn’t the case. You will feel hungry the first two days while your body is still transitioning, but after that the hunger subsides.

Here’s a few things you can do if you get hungry:

  • Drink some water. Drink a big glass first thing in the morning too. Staying hydrated prevents hunger.
  • Have a glass of green tea. This will have similar effects as drinking water, plus the added benefits of antioxidants, which may stimulate your metabolism and boost weight loss. Also, green tea is just delicious!
  • Avoid eat mints and gum. I know this sounds silly, but the combination of artificial sweeteners with flavor actually trigger the cephalic phase in your body that releases hormones and enzymes to prep your body to receive food - all of which increases hunger.

Stay Busy - Planning, gathering, and preparing meals consumes a lot of time. Not doing those things leaves you with a lot of extra time on your hands, so find some activities to keep you busy. Get a good book, or go for a walk, or start a new project you have been wanting to do!

Avoid Stress - I’ll admit that for the first two days of a fast I get a bit moody / emotionally sensitive. So I avoid things (and people) that stress me out. If you know something or someone that puts you on edge, avoid it for a few days.

Track Things - Weight loss is an evident benefits of fasting, but most of the real benefits are unseen. I like to track these - it’s fun to know how fasting is affecting your body and adds extra encouragement to see health improvements on paper.

Get a lipid profile taken before you start fasting. You can then get one every few months to track your cholesterol numbers, blood pressure, and other inflammatory markers.

Exercise - There are different opinions about this, but I find exercise to be enjoyable while fasting - some forms more than others. I have experimented with crossfit, weightlifting, running, and yoga while fasting.

When I water fast, I get the best results from steady state activities like running (or biking) and yoga. I found it difficult to recover well after higher intensity stuff like crossfit and weightlifting.

You can read more about how fasting affects your body during exercise here.

What to Do About Constipation - I’ve never experienced this, but it seems to be a common concern so I'll quickly address it.

If you aren’t eating, you simply may not have any waste to expel. However, if you feel the urge to go and cannot, consider drinking more water as you may be dehydrated. If the problem persists a small dose of a stool softener will probably do the trick. Just remember to drink more water than you think you need if you take a softener or laxative.

How to End Your Fast

“More caution and perhaps more restraint are necessary in breaking a fast than in keeping it.”  ~Mahatma Gandhi

Gandhi had just come off a 40 day fast, so you can see his point. The longer you fast the more precaution you should take.

The transition back to glycolysis from ketosis could make you sluggish and possibly a little sick. But with a few tips these are easily avoidable.


After reading the ample cautionary tales scattered across the internet about breaking a water fast, I decided to ignore them all at the end of my 5 day water fast and just feast - partly because I wanted to see how it would compare to breaking a fast after fasting mimicking (see below), and partly because I think our bodies aren’t as fragile as most people think they are.

So I ended my 5 day water fast by consuming homemade peanut butter cups, key lime cheesecake bites, bacon, and eggs. About 5 minutes later I was in the bathroom with stool of questionable consistency. It quickly passed and never returned, thank goodness. I ate a dinner, albeit small, of chicken pot pie about 3 hours later and was back to normal.

All that to say I recommend easing into your first meal with something small and light, then after that you should be fine. Longer fasts require greater precautions when refeeding. Here are a few principles to safely break an extended water fast.

  • Eat fresh whole foods - fruits, vegetables, and greens. It is important to eat them whole to get the fiber so as not to spike your blood sugar too high. 
  • Eat a small amount, which you will do naturally because your stomach will have shrunk significantly. Still eat less than you think you can, and definitely less than you want to.
  • Wait at least 2 hours after your first meal back. This will give you time to listen to your body and see how it's handling the food. If all seems good after a few hours, then eat a little more.
  • Continue eating whole foods and begin adding protein and dairy in small amounts, again giving your body time to respond after each meal before you continue eating.
  • Listen to your body. If it doesn’t like something then stop eating it!
  • Avoid sugar and carbohydrates. This is great nutrition advice in general, but especially after fasting. Sugar and carbs (also sugar) provide almost no nutritional value to your body, wreak inflammatory havoc, and are metabolically demanding. All things your body doesn't need after a period of abstinence.

An Alternative to Water Fasting: Fasting Mimicking

There are many variations of fasting. Is juice fasting okay? Can you eat some food, and if so what should it be? What's protein fasting? What about supplementation?

I'm not going to answer all those questions here, but I do want to discuss a new method called fasting mimicking.

Fasting mimicking is fasting with some food, although very little. It restricts calories to between 30% and 40% of your normal dietary intake.

That would be 725 calories if taken from a normal 2,000 calorie diet.

Fasting mimicking essentially tricks your body into thinking it's fasting, so even though you are eating some food your body still transitions into fasting ketosis.

The beauty of fasting mimicking is that you reap the same benefits as water fasting, but because you get some food possible side effects are limited and it's way more doable. Especially within a normal schedule for people who want to fast but still have to go about life, and work, and kids, etc.

I'm not making this up, fasting mimicking has been clinically tested and proven to work.

It's the protocol I use every month, and it's the foundation of our system here at LifeBox.

If you'd like to read more about it, click here.

Article Summary

  • Fasting is the act of abstaining from food for mentally and physically beneficial purposes.
  • Extended fasting is defined as any fast of 3 days or longer, and is necessary to receive permanent health benefits.
  • Find your motivation for fasting whether for weight loss, health improvement, fun, or mindfulness.
  • If you are new to fasting, consider working up to an extended fast by first intermittent fasting then by completing shorter single day fasts.
  • To safely fast always do your research, get plenty of rest, avoid stressful situations, get some sunlight, and discuss any additional precautions with your doctor.
  • While you are fasting, stay busy and don’t be afraid to exercise!
  • End your fast by eating small amounts of fresh whole foods and giving your body time to respond. Once you are sure that your stomach is good, proceed with joy.
  • Lastly, don’t be afraid of fasting. It’s doable for anyone and gets easier the more you do it.

Additional Resources


Stay young, 



Austin Gill

Short description here about the writer, with their social links below. Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.

Renew Your Health & Keep Your Happiness

LifeBox packs more benefits than any diet ever could and doesn't cramp your style.

shop our health plans

You May Also Like

Join Our Mailing List

We send occasional emails that are fun, simple, and chocked full of interestingly useful info. No spam, ever.