What to Expect From a 3 Day Fast if You've Never Fasted Before (2023)

It Was the Shit That Convinced Me

Ridiculous as this may sound, what motivated me to try a 3 day fast was hearing about the shit.

I had yet to learn how extended fasting would help me live longer and healthier, so I’d never considered not eating for longer than 24 hours.

No, It was a story my sister’s boyfriend told me about his own fasting experience that made me eager to try.

He told me that at some point towards the end of his 3 day fast, he went to the toilet and all sorts of crazy shit(literally) came out. It was kind of likecleaning out your garage for the first time in 30 years, he said.

My garage could use some cleaning.I was sold.

So with my girlfriend Kim away traveling, and thus unable to nag me about how I was starving myself or tempt me with delicious food, I decided to give a 3 day fasta go.

Holy shit was it a mind-blowing experience!

In This Post

  • My 3 Day Fast Story
  • 4 Ways to Make Your Fast Easier than Mine

4 Steps to a Fantastic First Fast

Get a free mini-guide of motivation and tips for having a successful first fast.

3 Day Fast, Day 0

The Last Meal

To celebrate (mourn?), I made a delicious and humongous Sunday night dinner, capped off with some Toblerone and a cocktail to celebrate. Then I began my 3 day fast. No more cooking, dishes, or chewing for 72 hours. Just water, tea, lemon, and black coffee.

I went to sleep feeling likea marathoner about to start his first race.

What to Expect From a 3 Day Fast if You've Never Fasted Before (1)

3 Day Fast, Day 1

Setting Off on a Voyage of Self-Discovery

Myfirst day was kind of like that of anearly explorer setting out in search of the New World. I wasn’t entering new territory—I’d done 24 hour fasts before—but this time itfelt different. This time I wasn’t turning back. I felt anxious and nervous.

Monday morning started as usual with my regular routine of heavy lifting at the gym (and a new personal best!) followed by a bunch of online computer work.

(Video) 3-Day Water Fast | I Ate Nothing & Here's What Happened

Then things gotunusual.

Something’s Missing

Normally I’d have a big early afternoon meal, but this time… nothing. Just black coffee.

What felt stranger than not eating was not having myritual midday lunch break. Rather than catch up on sports and social media while slurping down a smoothie and some eggs, I just kept on working. Who’d have thought fasting could lead to more productivity!?


My girlfriend Kim, who was supposed to be away until Wednesday, surprised me by coming home early. And since I hadn’t told her of my 3 day fast plan,she had brought some fresh salmon for dinner.


Surprisingly though, even as I watched and smelled her cook and eat herdelicious-looking meal with envy, I didn’t feel hungry. I felt good.

What to Expect From a 3 Day Fast if You've Never Fasted Before (2)

3 Day Fast, Day 2

Uncharted Territory

What a weird feeling it is to wake up after a day of zero calories for the first time in my life. I could joke that I literally felt empty inside, but it didn’t. I felt great. My sleep-tracking ring even said my sleep quality was 95%.

Feeling Electric

From themorning of day 2 to the end of my 3day fast, my mindfelt electric. As if I was high on Adderall, I hadn’t felt more focused in ages.

This, I found out afterward when I read some books on the physiology of fasting, is entirely to be expected. My brain was running on cleaner fuel than it was used to and my entire body was benefitting from hormonal boosts.

I worked all morning in a hyper-focused zone. Then when my eyes started to twitch from too much staring at a screen, I walked to the nearby beach to unwind.I tried meditating for 20 minutes and… holy hell! I swear to God at a certain point I felt high. Amazing.

The First Negative Experience

Unlike on Day 1, I definitely didn’t make any personal bests in my Day 2 workout. I felt like I did the day I tried working out aftertaking the bus fromLima to Huaraz in Peru (an elevation gain of 3000 meters or 10,000 feet).

My body felt strong, but it didn’t have the endurance it normally did. After one or two lifts my strength evaporated, and at times I was lightheaded to the point of dizziness.

I was glad to have gotten some exercise, but it was certainly the first negative effect I felt on my 3 day fast.

AnUnusual Day

Again, not having my ritual meal brakes for lunch and dinner was a trip. Honestly, I missed the ritual even more than the food itself. I didn’t know what to do with myself. It was like double daylight saving time: normally I’m ready for bed ataround 11 p.m, but this timeI was ready by 9. My brain wouldn’t stop buzzing, though, so I ended up reading in bed for hours.

Oh yeah, and most importantly (and disappointingly): no shit. No number 2 at all on day 2 of my 3 day fast.

What to Expect From a 3 Day Fast if You've Never Fasted Before (3)

3 Day Fast, Day 3

What the Hell?

Normally I wake up around 7:15 a.m. Today? At 5 a.m I was up and ready to go. My sleep-tracking ring toldme I had 90% sleep quality.

I still wasn’thungry and my mind feltsharp. So too did myhearing and sense of smell, which felt strangely super-powered. My body,though, felt lethargic.

The weirdest feeling, though? My mouth.

My mouth was likethe factory of a company that had just gone bankrupt. It’s all spic and span and ready to go, but empty. My breath felt strangely fresh and empty and my jaw tight from lack of use. Indeed, the night before I wondered to myself, “Do I actually need to brush and floss?”

Caving In

Do you remember how weird your teeth felt after getting your braces off? Or your arm or leg whenthe doctor removed your cast?

(Video) What Will Happen If You Eat Nothing for 7 Days

That’s how my stomach felt the last morning of my 3 day fast. It haddeflated overnight and felt completely foreign to me. I couldn’t stop touchingit with my hand. Normally I can do that stupid trick of sticking out my belly like I’m pregnant, but I couldn’t anymore.

It didn’thurt or anything. It just felttighter than normal, in a good way.

Pushing the Limit

Feeling mentally sharp but physically lethargic, I nonetheless went to the gym to see just how much juice my body had left.

Answer: Only a few drops.

I managedabout 80% of what I do when nourished. Strangely, I even felt sick to my stomach. When I shot some hoops after to cool down, I could barely make a free throw.

My weight, which normally hovers around 197 lbs, was down to 189.

What to Expect From a 3 Day Fast if You've Never Fasted Before (4)

The End

That afternoon I still wasn’t hungry, but I couldn’t help but daydream from time to time about my upcoming evening meal. I had grand visions of a gluttonousfeast where I’d recover all the calories I’d missed out on at once.

Those visions were not realized. I ate half as much as I thought I would and the food didn’t eventasteanybetter.

Immediately after eating, I had my first bowel movement since Day 1. Excitedly I went to the toilet. But it wasn’t a “garage cleaning” of crazy shit like I hoped. Just a couple of tiny turds.

Despite the anticlimactic end, my 3 day fast was overall a mind-blowing experience that I will definitely be doing again.

Maybe even longer next time!

Watch How It Went Down

In case you get really bored during your fast and want distraction from your kitchen cupboards, here’s the video-version of my 3 day fast experience:

How to Make Your Own Fast Easier

If you want to try fasting, I highly recommend you go into it a little better prepared than I did.

These four things might help:

1. Read the Fasting FAQ

What to Expect From a 3 Day Fast if You've Never Fasted Before (5)

Simple tips on fasting for answers to common questions like:

  • What am I allowed to eat and drink while fasting?
  • How much muscle / fat will I lose?
  • What can I do to feel less hungry?

Since I’m no doctor, all the medical info comes not from me but Dr. Jason Fung’s book (below). I just made it as concise and easy-to-understand (no medical jargon) as possible.


(Video) What Happens if You Eat NOTHING for 3 Days

2. Get this Fast-inating Book

The Complete Guide to Fasting, by Jason Fung

What to Expect From a 3 Day Fast if You've Never Fasted Before (6)

I wish I had read The Complete Guide to Fasting before I did this fast.

Not only does Dr. Fung explain exactly how and why fasting works, he provides helpful tips to make fasting easier. For example, he writes that if I had had some bone broth I might not have felt so lightheaded.

I followed this advice on subsequent multiple-day fasts and found it made all the difference.

Of all the podcasts, diet books, and articles I read about fasting, this one was by far the clearest, most compelling, and most helpful. I’ve told all my friends and family who think fasting is crazy but want to lose weight and be healthier to read it. And, though I don’t know you, I bet you’ll find it valuable too.

3. Use These Hydration Helpers

What to Expect From a 3 Day Fast if You've Never Fasted Before (7)

I later learned that dehydration was a big reason I got so lightheaded during my first ever 3-day fast.

Fasting purists will lose their shit (if they have any left; their bowels are probably empty by now from fasting so long), but I now throw in a few supplements to stay hydrated:

  • Electrolytes. Zero-calorie powders like this highly-rated one on Amazon seem to help with the dizziness.
  • Bone broth. I make some before I fast and have a cup as a treat. A reader on my fasting tips post recommended miso soup as a vegetarian alternative.
  • Sea salt and lemon. I have a huge glass of water with a bit of both first thing in the morning.

4 Steps to a Fantastic First Fast

Get a free mini-guide of motivation and tips for having a successful first fast.

If you have any doubts about your own fasting experience, read through the comments below and in my Water Fasting Tips, and Benefits of Fasting posts. They’re full of inspiring and entertaining stories, different experiences and opinions, and great questions.

And, of course, feel free to contribute!

(Video) 3 Day Fasting: Not What I Was Expecting

Happy Fasting!

“Good luck” isn’t the right thing to say, since there’s no luck involved in not eating. So let’s go with, “All the best!”

A three day fast really is all the best for your health. It’s definitely daunting for first-timers, but it’s worth it in the long run and you won’t regret it. Hopefully, this post will help you prepare mentally and understand what to expect.

If you have any questions or have different experiences on your own fast, please share with all of us in the comments or on social media.

And, once again, all the best!

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Read This Next:

Easy Water Fasting Tips from a Guy Who Learned the Hard Way

Why Fast? Prolonged Fasting’s Surprising Benefits and Disadvantages

How to Stop Liking Junk Food: The Reverse-to-Revulsion Technique

The 3-Day Effect Will Motivate You to Escape into Nature

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Intermittent Fasting Explained With a Simple Story

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What is the hardest day of a 3-day fast? ›

Our stomachs haven't been growling and we felt surprisingly satiated after a cup of tea at 4 PM. But, we weren't holding our breaths. From what we've heard, Day 2 is usually the hardest on a 3-day fasting journey. This seems to ring true even during a longer 7-day or 14-day fast.

What happens to your body when you fast for 3 days? ›

72+ hours. Once you've been fasting for three days or more, your body enters a deep state of ketosis. All the previous benefits: Autophagy, the uptick in the production of beneficial chemicals and hormones, fat loss, and mental clarity continue to increase.

Do you need to prepare for a 3-day fast? ›

How To Prepare For A Fast. In order to make the switch over into ketosis much easier, it's best to eat a low-carb diet for three days leading up to your fast. We stuck to organic vegetables, pastured meats, organic nuts, and pastured animal fats for three days.

How can I survive a 3-day fast? ›

Here are 10 tips to help you fast safely.
  1. Keep Fasting Periods Short. ...
  2. Eat a Small Amount on Fast Days. ...
  3. Stay Hydrated. ...
  4. Go for Walks or Meditate. ...
  5. Don't Break Fasts With a Feast. ...
  6. Stop Fasting If You Feel Unwell. ...
  7. Eat Enough Protein. ...
  8. Eat Plenty of Whole Foods on Non-Fasting Days.
2 Jan 2019

How much weight is lost on a 3-day fast? ›

For a 3-day water fast, muscle loss will be minimal because, during this relatively short period of time, the body will consume stored carbohydrates with associated water weight. For longer fasts, muscle loss could reach . 4 lbs a day once full ketosis is reached around the third day.

What does a 72 hour fast do to your body? ›

The lack of food intake during a long time, like 72 hours without any food, could result in an irregular heartbeat that can cause serious heart problems. People who suffer from any of these listed conditions or illnesses should not fast for 72 hours: Alzheimer's disease. Chronic fatigue syndrome.

How long does it take for your body to start burning stored fat when fasting? ›

Fat burning typically begins after approximately 12 hours of fasting and escalates between 16 and 24 hours of fasting.

How do I know if autophagy is working? ›

Autophagy is a natural process that occurs as your body clears out and replaces damaged cell parts with new ones.
  1. Increased ketone levels. ...
  2. Reduced appetite. ...
  3. Fatigue. ...
  4. Bad breath. ...
  5. Weight loss. ...
  6. Improved brain function.
4 Jan 2022

What are the 5 stages of fasting? ›

The 5 Stages of Intermittent Fasting with the LIFE Fasting Tracker app: 1) Ketosis and heavy ketosis, 2) Autophagy, 3) Growth hormone, 4) Insulin reduction, 5) Immune cell rejuvenation!

How long does it take for autophagy to start? ›

How long do you have to fast for autophagy to occur? Studies involving animals suggest that autophagy may begin between 24 to 48 hours of fasting.

Can you exercise while fasting for 3 days? ›

Can I Exercise While Fasting? Yes, it is OK to work out while fasting because the key to weight loss and muscle gain is not just calories and exercise, but hormone optimization.

Will lemon water break a fast? ›

The truth about lemon water and intermittent fasting

Long story short - the answer to the question “Does lemon water break a fast?” is no, lemon water does not break a fast. Lemon water contains almost no calories and zero sugars, it doesn't raise insulin levels, which means it will not break your fast (1).

What happens after not eating for 3 days? ›

After two or three days, your body starts to break down fatty tissue. Your muscles use the fatty acids created during this process as their main source of fuel. Fatty acids are also used to form ketones in the liver. Ketones are another substance the body can use for energy.

Will gum break my fast? ›

For stricter forms of fasting like water fasts, consuming any calories technically breaks your fast. This is especially true if you're chewing multiple sticks of gum per day or choosing a type of gum that's high in sugar.

Will a 3 day fast burn fat? ›

One 3-day fast is not going to have a significant impact on your weight. You may notice some changes on the scale, but don't mistake these changes for long-term weight loss. Any weight that you lose during a fast is mostly water weight (6). Once you start eating again, you quickly regain this weight.

What happens if I fast for 3 days a week? ›

May Lead To Weight Loss

Some people who try the fasting diet for 3 days do it as a way to lose weight. While people do lose weight, it is important to note that the weight loss is water weight and not fat loss. Research has shown a positive correlation between increased water consumption and weight loss.

What to eat after fasting for 3 days? ›

Gentle foods to break a fast
  • Smoothies. Blended drinks can be a gentler way to introduce nutrients to your body since they contain less fiber than whole, raw fruits and vegetables.
  • Dried fruits. ...
  • Soups. ...
  • Vegetables. ...
  • Fermented foods. ...
  • Healthy fats.
26 Sept 2019

How much fat is lost in a 72 hour fast? ›

Losing fat takes more time.” Fasting proponent Fung, however, disagrees and maintains that you could lose 1.5 pounds of fat over a 72-hour period. For that reason, he recommends that people with a Body Mass Index (BMI) of less than 20 could put themselves at risk of malnutrition.

Will a 48 hour fast put me in ketosis? ›

For the average adult, a 48-hour fast will generally result in ketosis. After this fast, adopting a Ketogenic Diet will allow you to stay in ketosis. We recommend starting the fast at least 3 hours before bedtime on the first day, and eating at the same time 2 days later.

How long do you have to fast to get into ketosis? ›

Your body may go into ketosis after just 12 hours of not eating, which many people do overnight before they "break fast" with a morning meal. (A midnight snack obviously sabotages this process.) A keto diet keeps you in ketosis for much longer time periods because you avoid carbohydrates, which supply glucose.

Where does the fat go when you fast? ›

The correct answer is that fat is converted to carbon dioxide and water. You exhale the carbon dioxide and the water mixes into your circulation until it's lost as urine or sweat.

Which part of body loses fat first? ›

Mostly, losing weight is an internal process. You will first lose hard fat that surrounds your organs like liver, kidneys and then you will start to lose soft fat like waistline and thigh fat. The fat loss from around the organs makes you leaner and stronger.

How do you know when your body is burning fat? ›

10 signs you're losing weight
  1. You're not hungry all the time. ...
  2. Your sense of well-being improves. ...
  3. Your clothes fit differently. ...
  4. You're noticing some muscle definition. ...
  5. Your body measurements are changing. ...
  6. Your chronic pain improves. ...
  7. You're going to the bathroom more — or less — frequently. ...
  8. Your blood pressure is coming down.

Is 3 days enough for autophagy? ›

Studies have shown that autophagy may take two to four days of fasting in humans. It is believed that autophagy does not begin until the glucose and insulin levels drop considerably. Some experts suggest starting with 32 to 48 hours; 72-hour fast autophagy pushes the limits for most humans but can be possible.

Does autophagy make you look younger? ›

Similar to how our bodies can eat away at unnecessary skin cells from loose skin through the process of autophagy, the appearance of aging is also slowed (and many say can even be reversed to an extent) when we activate this mechanism of clearing out old cellular parts – therefore revealing more youthful, vibrant skin.

How do you trick your body into autophagy? ›

  2. Choose the right foods and supplements. ...
  3. Fasting, intermittent fasting and almost fasting.
  4. Going keto. ...
  5. Protein Cycling. ...
  6. Exercise, but don't go crazy. ...
  7. Turn up the heat. ...
  8. Get quality sleep.
30 Oct 2019

How long should beginners fast? ›

With a traditional fast, start with 24 hours, and then bump it up to three days if the first one goes well. With the time-restricted approach, don't immediately limit yourself to eight hours a day of eating if you're used to eating every hour that you're awake; start with 12 hours on, 12 hours off, and go from there.

Does fasting burn belly fat? ›

Intermittent fasting is a convenient way to lose weight without counting calories. Many studies show that it can help you lose weight and belly fat.

What happens to your body when you start to fast? ›

Essentially, fasting cleanses our body of toxins and forces cells into processes that are not usually stimulated when a steady stream of fuel from food is always present. When we fast, the body does not have its usual access to glucose, forcing the cells to resort to other means and materials to produce energy.

What is dirty fasting? ›

What is dirty fasting? It's a “lazy” way to practice intermittent fasting that involves consuming about 50 to 100 calories outside of your eating window. This method is more flexible that clean fasting (which involves consuming zero calories), so it might make it easier to follow and stick with.

Does autophagy tighten loose skin? ›

During autophagy, older, damaged, and dying cells are consumed and recycled for energy and are replaced by newer, healthier cells. This helps with your skin health, both tightening loose skin and preventing wrinkles.

Do you lose weight during autophagy? ›

Generally speaking, autophagy does not cause weight loss, as it is an ongoing cellular process that keeps our cells alive. However, the autophagic process makes the metabolic process more efficient by removing and repairing cells that no longer function as needed.

What are the benefits of a 3 day fast? ›

Health Benefits of Fasting
  • Boost cognitive performance.
  • Protect from obesity and associated chronic diseases.
  • Reduce inflammation.
  • Improve overall fitness.
  • Support weight loss.
  • Decrease the risk of metabolic diseases.

Does coffee break a fast? ›

The short answer is yes, you can drink coffee while intermittent fasting. But, this answer comes with a big caveat: You can drink black coffee while intermittent fasting, but coffee drinks with cream, sugar, or other forms of calories technically break your fast.

What are the stages of fasting? ›

There are four stages of fasting that the body encounters. Anabolic, Catabolic, Partial Ketosis, and Active Ketosis. When we think of fasting, we often think of starvation or deprivation. There is a great deal of research around using this process as a tool for cell renewal, weight loss, and immune support.

How do you break a 72 hour fast? ›

After multiple days without any food your digestive system needs something simple and easy to process. The best food to break a fast is light fruit such as watermelon or a smoothie is the best way to start. This is giving your system a chance to get used to food again before beginning on solid foods.

What doesn't break a fast? ›

Water is naturally the only drink that is free of any amount of calorie. However, if you feel like brewing a cup of coffee in the morning, you will not be breaking your fast if you stick to black coffee and natural tea without adding sugar, sweeteners, dietary products like milk; whether skimmed or whole.

How many calories breaks a fast? ›

The general rule of thumb is that if you stay under 50 calories, then you'll remain in the fasted state.

How many pounds can you lose in 3 days from not eating? ›

During the first 5 days without food, a person may lose 1 to 2 kilograms (2.2 to 4.4 pounds) of body weight each day. Most of this weight loss is related to dehydration and electrolyte imbalance.

How often should I do a three day fast? ›

If you are looking for a hard reset, fasting for three days once every three months is probably good. If you are looking to heal a specific disease or malaise, fasting in excess of five days under medically supervised conditions once may be more effective.

How long before hunger pains go away when fasting? ›

Many people on longer fasts report that hunger typically disappears after day 2. Fasting can also suppress hormones inducing satiety, like lepti, but probably more so if calories are restricted during the eating window and when leading an unhealthy lifestyle or not sleeping well.

Does diet Coke break a fast? ›

Any sugary drink will technically break your fasting, so make sure that the diet sodas you consume are really sugar and calorie free. So, while diet soda is acceptable while you are fasting, there are many other zero calorie beverages that are healthier and naturally flavored.

Does green tea break a fast? ›

No. Drinking green tea does not break a fast. Because green tea is a zero-calorie beverage, drinking tea does not interrupt your fasting period, and will not break your fast. Intermittent fasting is a dietary strategy in which you follow specific eating windows and fasting windows throughout the day or the week.

Can you have any calories while fasting? ›

Strictly speaking, any amount of calories will break a fast. If a person follows a strict fasting schedule, they should avoid any food or drinks containing calories. Those following a modified fasting diet can often eat up to 25% of their daily calorie needs while fasting.

What does not eating for 3 days do? ›

After two or three days, your body starts to break down fatty tissue. Your muscles use the fatty acids created during this process as their main source of fuel. Fatty acids are also used to form ketones in the liver. Ketones are another substance the body can use for energy.

Does fasting for 3 days cause muscle loss? ›

SUMMARY There's no evidence that fasting causes more muscle loss than conventional calorie restriction. In fact, studies demonstrate that intermittent fasting may help you maintain muscle mass while dieting.

What not to do after fasting? ›

The bottom line is that while breaking a fast, you want to avoid foods that contain large amounts of sugar, complex carbs, fiber, and fat.

Does lemon water break a fast? ›

The truth about lemon water and intermittent fasting

Long story short - the answer to the question “Does lemon water break a fast?” is no, lemon water does not break a fast. Lemon water contains almost no calories and zero sugars, it doesn't raise insulin levels, which means it will not break your fast (1).

Can I workout while fasting for 3 days? ›

Yes, it is OK to work out while fasting because the key to weight loss and muscle gain is not just calories and exercise, but hormone optimization. Studies demonstrate amazing benefits to intermittent fasting alone, but combining fasting with sprint training takes the benefits of each to a whole new level.


1. 30 Days of Alternate-Day Fasting - 10lbs of Body Fat (Before & After)
(Goal Guys)
2. Minimum fasting length required for autophagy | Guido Kroemer
(FoundMyFitness Clips)
3. 3 DAY FAST (NO FOOD) || *AMAZING* Before and After Results | Weight Loss Journey
(Lauren Jansen)
4. I Didn't Eat Food for 7 days. This is what happened to my body
(What I've Learned)
5. I fasted for 3 days | Lex Fridman
(Lex Fridman)
6. 3 Day water fast! Weightloss | My thoughts | Motivation
(Team Kaya)


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