How To Do A 3-Day Fast

In this article, we are going to share our experience and the research to teach you how to do a 3-day fast successfully.

We cover how to prepare for a fast, share the results of our recent 72-hour water fast, and teach you how to break the fast safely.

Don’t be intimidated by extended fasting. It’s easy. And a great opportunity to lose body fat, reset your hormones and learn valuable lessons in the process. 

how to do a 3-day fast

We’ve done some crazy things in our lives, but this was by far the craziest: a 3-day fast.

Yes, we ate nothing and just drank water tea, and black coffee for 72 hours. The most surprising part? We felt amazing and it wasn’t that challenging at all.

You can do it too. Even if you’ve never missed a meal your entire life or can’t imagine a day without breakfast, we’re here to tell you that it’s not so tough.

Our History With Fasting

Our story with fasting begins a few years ago when I had reached my last straw with Ryan…

“I will not let your stupid hunger ruin my vacation!”

Ryan and I were spending a weekend in San Antonio, and I had the whole day planned with things to do and places to go. But, every two hours, Ryan became cranky, irritable, and complained that he was hungry.

As I stared angrily at him after he asked for the millionth time to eat, he just stared at my purse and asked if I had a snack for him in there. Ummm… no, you’re not my toddler.

Thankfully now, Ryan’s hunger no longer controls him (or me). Ever since he began intermittent fasting, his hunger no longer rules him.

Given our success with Intermittent fasting, when Ryan suggested we do a 3-day fast last week, I was on board.

I didn’t find the idea of fasting ridiculous. We do the 3-Day Refresh detox yearly, which is like a guided, low-calorie fast with timed supplemental shakes and fiber sweeps.

We also have plenty of friends who have fasted for health or religious reasons, all to great success. One of our friends even continued running to and from work each day (a daily, roundtrip marathon) while fasting during the month of Ramadan.

So, it was game on.

How Do You Define Fasting?

First of all, we need to make one thing clear: fasting is not starvation.

Fasting is voluntary and you can end it anytime. In the book, The Complete Guide to Fasting, by Dr. Jason Fung and Jimmy Moore, the authors likened fasting to a recreational run, instead of starvation which is like running from a lion to save your life.

Starvation is brought on by war, famine, and similar dire circumstances outside of your control. Fasting is voluntary to achieve therapeutic, spiritual, or health benefits.

Fasting is a tool that can be used for cancer prevention, obesity, type 2 diabetes, increased focus, and toxin reduction.

What Is a 3-Day Water Fast?

It’s nearly exactly what it sounds like. Consuming nothing but water for 72 hours. 

I say ‘nearly’ because there is the option to consume a few things other than water. More on that soon. 

The real question is, “Why would anybody in their right mind want to fast for three days?” It’s not just for weight loss. Most people fast to improve their overall health.

What Are The Benefits of Fasting for 3 Days?

For years, Ryan and I have read about the health benefits of fasting, including:

Neurological boosts

  • Improved memory
  • Better concentration

Decreases risk for disease

  • Reduced inflammation
  • Reduced blood pressure
  • Lower heart rate
  • Less fatty liver
  • Decreased atherosclerosis
  • Cancer prevention

Aids in weight loss

  • Increased insulin sensitivity
  • Increased lipolysis (fat-burning)
  • Decreased leptin (better control of hunger)

Promotes longevity

  • Anti-aging effects
  • Autophagy (cellular cleansing)

Furthermore, Dr. Thomas Seyfried, a professor at Boston College, found in his treatise, Cancer as a Metabolic Disease: On the Origin, Management, and Prevention of Cancer, that a yearly 7-day fast could kill off abnormal and pre-cancerous cells.

That’s a pretty impressive list, huh? Fasting helps you stay younger and improves your brain and body health.

How To Prepare For a 3-Day Water Fast

Always the engineers, we prepared for our 3-day fast by researching and reading books about fasting written by doctors.

We wanted fasting to feel natural and something that could be done on a whim. No binge-eating the night before.

Ryan and I read several books on fasting beforehand and learned a few key water fasting tips. Following them will help you plan your 3-day fast and teach you how to make your fast successful.

1. Decide how long you will fast.

While intermittent fasting has become incredibly popular, there are few limits on what constitutes the right amount of time to fast for health purposes.

Much changes from person to person. Depending on your diet, insulin sensitivity, and exercise level, it could take between 12-36 hours to “flip” the metabolic switch, something we discuss more in our article on the health benefits of IF.

It took us 56 hours to flip our switch during this 3-day fast.

And when I say there is no right amount of time to fast, it truly has no upper limit. The longest fast ever recorded was in 1965 by a Scottish man, Angus Barbieri, who took daily vitamins with zero-calorie drinks like tea, coffee, and water.

Obese at 456 pounds, he fasted under doctor supervision until reaching his goal weight of 180 pounds. Which he achieved in full health, 382 days later.

Nowadays, most extended fasts are 7-14 days. The people who opt to do these longterm fasts are usually fighting obesity, fatty liver disease, insulin resistance, type 2 diabetes, or other metabolic diseases.

Shorter fasts of up to 1-3 days are seen more among people looking to detox and lose moderate weight.

When undertaking a fast longer than 3 days, it is recommended to have some clinical supervision.

2. Drinking coffee and tea during a 3-day fast is fine.

Other acceptable drinks for a health fast include tea and coffee. Feel free to add a slice of lemon, but avoid milk or sugar.

Even zero-calorie sweeteners like stevia should be avoided, as it isn’t in line with the detox mentality. Zero-calorie soda is out of the question.

3 Day Fast Ryan and Alex Duo Life Water Fast

3. You can have more than just water while fasting.

For fasts longer than 3-days, consider supplementing with electrolytes to maintain mineral levels. This can be done with zero-calorie electrolyte drinks, bone broth with sea salt, or miso soup for vegetarians like us.

Since our fast was only three days, and studies showed that mineral levels aren’t affected up until then, we didn’t consume any electrolytes. And we drank tons of water!

An absolute fast, usually done religiously, means nothing is consumed. However, the studies we read highly recommended drinking water because dehydration only harms and complicates your fast.

4. A 3-day water fast takes longer than three days.

A 72-hour water fast doesn’t take just 3 days, it takes 4.5 days. That’s because you want to reintroduce foods carefully to avoid stomachaches afterward.

The rule of thumb is to take the number of days you fasted and divide it by two. That’s the number of days you should still be careful with eating, particularly with simple carbohydrates, before resuming your normal diet.

Instead of breaking our 72-hour fast by feasting, we ate this. It doesn’t look very exciting but the flavors were incredible!

3 Day Fast Ryan and Alex Duo Life Breaking the Fast

5. Don’t eat a final meal heavy in carbohydrates.

The purpose of the fast is to drop insulin and glucose levels to kick your body into ketosis (your fat-burning stage). Eating a whole bowl of pasta will prolong the time it takes for your insulin levels to deplete and delay your good results.

6. Let family or roommates know you’re fasting.

If there are other people in the house, let them know you’re fasting. While you’re hopefully not cranky, they should be aware and therefore prepare their food more privately while you’re fasting.

Our fast took place while staying with my parents, so we went for walks while they ate dinner.

7. Start your fast on Thursday after lunch or dinner.

If you work from home and have a flexible schedule, this doesn’t matter. If not, consider having your second and third days of fasting — most likely your hardest — over the weekend when you’re not working.

This helps if you need to sleep in or just don’t feel like your best self. While we were fasting, we were incredibly focused and productive at work, but it was nice to have the option to sleep in until 10 AM. 

8. Consider running bloodwork before and after.

To make the most out of your fast, it would be nice to compare your blood sugar levels, cholesterol, ketones, etc.

For Ryan and me, we simply measured our weight, rated our hunger twice daily on a scale from 0-10, and tracked our sleep and heart rate through our Apple Watches.

Our 3-Day Fast Story and Results

Day 1

Alex’s Weight: 107 lbs. 
Ryan’s Weight: 169 lbs. 

Nervous Excitement

After a normal day of eating ending with pizza (probably not the best choice) and salad for dinner, we began our fast at 8 PM on Saturday. We went to bed nervous but excited.

Our first night of sleep was perfectly normal, since we ate dinner normally and began our fast at 8 PM. 

The next morning, we kept to our typical schedule and exercised. Ryan and I did a tough workout for 30-minutes to P90X3. After that, we started our workday and made sure to drink lots of water.

Our First Hurdle

Halfway through the day, I started getting a bad headache, which I associated with my daily coffee habit. While I was hoping to drink water only for the fast, there’s no sense in battling hunger AND a throbbing caffeine headache.

When Ryan admitted to having a dull headache as well, I made us each a cup of black tea and our headaches went away within thirty minutes.

The rest of the evening was surprisingly normal, and we even took a walk at night while my parents ate dinner.

24 Hours Checkpoint

On a scale from 1-10 for hunger, Ryan felt 6/10 for hunger and a 2/10 for me. It’s crazy, but we weren’t hungry! 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 day of fasting. This seems to ring true even during a longer 7-day or 14-day fast. So, we went to bed unsure of what was coming the next day.

Below is our sleep data, showing a typical night sleep for us. 

3-day fast sleep data night 1 Ryan and Alex Duo Life

Day 2 

Alex’s Weight: 105 lbs. (down 2 lbs.)
Ryan’s Weight: 162 lbs. (down 5 lbs.)

Our Second and Last Hurdle

Sleep. Many fasters have trouble sleeping. That was never us while following a 16/8 intermittent fasting plan, however, beyond 24 hours was a different story. 

Ryan was too energized to sleep and he could only get comfortable on his side, in a fetal position, because his stomach ached on his back. 

We both woke up feeling restless, although our Pillow sleep tracker app showed us that it was a typical night of 8.5 hours of sleep.

When Does This Get Hard?

After a 30-minute dynamic stretching workout, we brewed a cup of tea, and started our workday. We felt focused, comfortable, and knocked off item after item our to-do lists.

We hydrated consistently, and in the evening, we once again took a walk while my parents ate dinner and reveled in having extra hours to hang out instead of cooking or washing the dishes.

48 Hours Checkpoint

On a scale of 1-10 of hunger, Ryan felt 4/10 and a 3/10 for me. Honestly, not much had changed in the past day. We went for another walk and watched a movie before bed.

We didn’t experience hunger pangs or any physical or mental fatigue. The only thing we both noticed was that we would occasionally get light-headed when we stood up and started moving too fast. 

Below is our sleep data for the second night of our 72-hour water fast. 

3-day fast sleep data night 2 Ryan and Alex Duo Life

Day 3

Alex’s Weight: 103 lbs. (down 4 lbs.)
Ryan’s Weight: 162 lbs. (down 7 lbs.)

Boom. There It Is… Hunger

At 9 PM, hour 49, both of our stomachs started grumbling. For the first time in days, we both felt hungry at a 7/10. It wasn’t painful or a bite-your-head-off type of hunger, but it was noticeable.

This must be what everyone had talked about when they said it gets hard. On top of that, my legs felt a bit achy and we overall felt a bit depleted.

We went to bed restlessly but luckily the majority of the hunger pangs happened while I was asleep, because 5 hours later…

What Should Happen To Your Body When You Fast

At hour 56, just before 4 AM, I woke up. I couldn’t figure out why I woke up until I realized that my heart was racing.

My whole body reverberated with each beat and I checked my Apple Watch to see that my heart rate was at 95 bpm (beats per minute).

Just minutes before when I was sleeping, it was at my typical 55 bpm. My metabolic flip had switched. Ketosis had been reached. My mind felt sharp, clear, and wide awake.

I was no longer hungry. The glucose in my bloodstream must have run out, and my body switched from burning glucose to burning fat. My brain was running on ketones, and adrenaline kicked in.

When reaching a fasted state, insulin plummets while adrenaline (for focus) and human growth hormone (to maintain muscle) skyrocket.

This happened so that our ancestors would be on their top game to hunt and find food. I had finally reaped the rewards of my fasting.

The next day, we filtered through our Apple Watch heart rate data and found that Ryan flipped his metabolic switch while lying awake reading a few hours earlier.

3-day fast metabolic switch Ryan and Alex Duo Life

Sleep Was Not Happening

Since I was wide awake, I grabbed my book to start reading in bed and accidentally woke Ryan. Like me, he was wired and no longer hungry.

But, unlike me, he hadn’t fallen asleep until 2 AM because his peak hit at 11:30 PM a few hours before.

After a few hours of reading, my heart rate finally slowed and I became drowsy. We both fell asleep again at 6:30 AM and woke up around 10 AM.

Easy Street

Throughout the rest of Day 3, we both felt no hunger, a 1/10. An overall feeling of easy wellness and energy came over us. We kept ourselves busy and Ryan even did some tough manual labor in the heat.

We went for a long walk around my hometown’s public gardens and farm before coming back to finally eat food and finish our fast.

3 Day Fast Ryan and Alex Duo Life Ryan Exercising

72 Hours Checkpoint

We made it! Unbelievably, we had very easily gone without food for 72-hours and it felt amazing. We could have continued longer, but mentally we were ready to eat as that deadline had been on our minds since hour 1.

Plus, it had felt unsocial while staying with my parents and we just missed the whole ritual of sitting down and eating. But, we had done it and knew that we could do an even longer fast next time if we wanted.

Below is our sleep data for night 3. As you can see, this was a very restless night sleep for both of us. 

3-day fast sleep data night 3 Ryan and Alex Duo Life

Final Results

Alex’s Final Weight*: 101 lbs. (7 lbs. lost)
Ryan’s Final Weight*: 160 lbs. (9 lbs. lost)

*A note about weight loss on a 3-day fast: On average, 0.5 lbs. of fat will be lost per day during fasting. One pound of fat is 3,500 calories, which is about double the number of calories you likely burn on a typical day (perhaps closer to 1 lb. for Ryan who burns 2,500+ calories a day).

The rest of the weight loss you see is water weight. This number was corroborated by numerous studies we read as well.

The below graph is a summary of your 72-hour water fast results, showing both weight loss and hunger rating. As you can see, Ryan had hunger spikes around dinner time for the first two nights. 

Then, both of us we not remotely hungry by night 3, at the end of our 3-day fast. 

3-day water fast results Ryan and Alex Duo Life Weight Loss Chart

Breaking Our 3-Day Water Fast

We knew to break our fast carefully to avoid stomach aches or refeeding syndrome. After a lot of research, this is how we did it.

How Much To Eat While Breaking Fast?

Some research says to eat around 500-800 calories on your recovery days (or about half of what you normally consume). We ate more than that, but made sure that everything was fresh, nutritious, and still in a small portion. And we felt great.

Once again, your recovery days should last about half the length of your fast, so we were careful for 1.5 days after our 3-day fast.

Hour 72 – Miso Soup

Ryan and I started with cups of miso soup. Bone broth with sea salt is also a popular option, but as vegetarians, we went with miso soup which we made from miso paste found at our grocery store. It was salty and oh so delicious.

3 Day Fast Ryan and Alex Duo Life Miso Soup

Hour 73 – Vegetables and Guacamole

An hour later, we went to solid food. We made a small salad with cherry tomatoes, cucumbers, fresh parsley, olive oil, a squeeze of lemon, and salt and pepper.

On the side, we had a few scoops of guacamole. This meal focused on healthy fats and fresh, non-starchy and non-cruciferous vegetables. We avoided simply carbohydrates so that our insulin wouldn’t spike and undo all of the hard work we had done.

We also avoided dairy as it’s hard to digest. After a fast, the number of digestive enzymes in your body decreases, so you have to start easy.

3 Day Fast Ryan and Alex Duo Life Breaking the Fast Salad

Hour 77 – Breakfast Before Bed

Since we felt great, we were ready to introduce another small snack before bed, allowing our bodies to digest all of our newly eaten food.

We ate some typical breakfast foods of an egg, black beans, plantain, and more guacamole. As we hoped, this helped ensure a restful night’s sleep. 

Hour 87 – Breakfast Smoothie

We started our day carefully with a Vanilla Shakeology smoothie, made from fresh blueberries, homemade cultured milk kefir, peanut butter, bananas, and mint leaves.

We also made sure to hydrate to aid in digestion while getting in enough fiber.

Hour 90 – Black Bean Veggie Tacos

Ryan and I still felt great and satiated without any stomach issues. We introduced a few carbs in the form of corn tortillas and had veggie tacos with black beans for lunch.

Hour 95 – Almost Back To Normal

Finally, a celebratory dinner with the family. We ate a home-cooked Greek meal by my mother of spinach spanikopita with a cucumber yogurt soup and a huge lettuce salad. Our eating was nearly back to normal, but we still passed on the bread and alcohol.

Lessons Learned From Our 3-Day Fast

Our fasting experience was eye-opening.

We Can Control Hunger

The hunger never overwhelmed us because hunger doesn’t just grow, grow, grow until you’re ready to eat your own hand.

It comes in waves that get weaker each time. The hunger we felt was the same as when you miss lunch because you’re stuck in a meeting. More often than not when the meeting is over, you’re not hungry anymore.

That’s because the hunger we experience (when not in a war or famine) isn’t when our stomachs are empty. Heck, people say “they’re starving” just hours after their last meal!

Those hunger pangs are hormonal and signals from the brain, not your stomach. Like Pavlov’s dogs, you’re ready to eat because the clock strikes twelve, not because you need the food.

We Appreciate Food And Our Bodies

It was truly incredible to experience what your body goes through during a 72-hour water fast. And that first meal afterward, cherry tomatoes and cucumbers, have never tasted so good!

3 Day Fast Ryan and Alex Duo Life Alex Breaking the Fast

We Easily Survived 

Each pound of body fat we carry is 3,500 calories, and when in a fasted state, our bodies learn to tap into that resource and energize itself. And let’s be honest, most of us carry a few (or more) pounds of extra fat.

To give you some perspective, the average body fat in men is 25% and 35% in women. Even an elite, lean marathoner carries around 9% body fat. So, you’ll survive just fine.

A New Tool In Our Toolbox

Ryan and I found fasting to be a great tool in our health arsenal, and it’s a tool that humans have used for thousands of years. Extended fasts or alternate day fasts can and should be mixed in with a typical intermittent fasting schedule.

It can be something you do every month, depending on your health goals.

As Plato so simply puts it, “I fast for greater physical and mental efficiency.” Fasting does the body well and is incredibly effective. Try it and surprise yourself.

Common Questions About Extended Fasting

Here are a few frequently asked questions that we were asked while broadcasting our fasting journey on our Instagram page. Have more? Comment below and we’ll get them answered.

Is there anyone who shouldn’t fast?

Men and women have been fasting for millennia for health and religious reasons. Both men and women see similarly great results when fasting, yet there are a few groups who are not recommended to fast by doctors.

Pregnant women and breastfeeding mothers are not recommended to fast, as their mineral intake requirements are higher for themselves and their babies.

Additionally, anyone with a history of anorexia or who is malnourished (often generalized as groups with a BMI of 18.5 or below) should avoid fasting as well.

Finally, people on medication, particularly type 2 diabetics on insulin or blood sugar medicines, should first consult with their doctors to modify the medicine dosages during the fasting period.

For people who take daily medicine with food, consider a 24-hour fast instead so that the medicine can be taken along with your one daily meal.

Will I Lose Muscle If I Fast?

No, studies show that muscle mass will not be depleted when exercise and workouts are maintained.

In fact, weight lifters were some of the first athletes to experiment with fasting and timed eating to reduce body fat and increase muscle mass.

During fasting, human growth hormone levels can more than double, which preserves muscle and strength. Our bodies are smart enough to know that fat burns before muscle. 

What happens to bowel movements during fasting?

This is an interesting question and one that many people ask since your poop can teach you a lot about your health. It gets crazy how much stuff gets cleaned out. Well, this is a detox after all.

While we didn’t personally experience anything out of the normal, we’ve heard of stories that the body continues to clears out even after days and days without food.

During longer fasts, expect to go to the bathroom less frequently and continue to drink lots of water throughout to aid in digestion.

Remember Angus Barbieri, the guy we mentioned who fasted for 382 days? His bowel movements happened every 37-48 days. Crazy.

What should I eat to break a fast?

What’s interesting about this question is that many doctors have varied, and often opposing, opinions on what foods to eat.

Doctors all tend to agree on broth, soup with cooked vegetables, nuts, non-starchy vegetables like tomatoes and cucumbers, avocados, cultured yogurts, small portions of protein (chicken, fish, and eggs are mostly named), and fresh fruit juices.

Things to avoid include simple carbohydrates, high sugar foods, alcohol, cruciferous vegetables, root vegetables, and dairy.

What should I eat before a fast?

Fasting should fit naturally in your lifestyle, so don’t overeat and binge before a fast. Ideally, you would eat a high protein, low carb meal to minimize glucose availability to kick you into the fat-burning ketosis stage faster.

How long and often can I fast for health?

There’s no upper limit to fasting, as the longest fast lasted for 382 days with Angus Barbieri in 1965. Also, there’s no “best” fasting schedule, and some research suggests that mixing it up is beneficial for your health.

Just like a good workout program, variety avoids plateau and strengthens the body.

Fasting includes intermittent fasting, alternate-day fasting, and extended fasts over 24-hours. For fasts over 3-days, supplement with electrolytes, bone broth with salt, or miso soup. It’s a good idea to have your doctor supervise a longer fast as well.

Longer fasts (7-14 days) are typically performed by people with large weight loss goals, developed insulin resistance, have fatty liver disease, or who have type 2 diabetes.

Shorter fasts of up to 1-3 days are seen more among people looking to detox and lose moderate weight.

From our research, fasts under 48-hours can be done weekly while longer fasts can be done every two weeks with intermittent fasting in between.

Should I fast or do a low-calorie diet?

Research shows again and again that fasting is more effective than a low-calorie diet. The thing is, even celery, a nearly zero-calorie food, will increase your insulin levels.

The only way to bring down insulin resistance is to stop consuming foods altogether.

Another problem with a restricted-calorie diet is that it affects your metabolism and can throw hormones out of whack, which is the problem with fad diets.

This doesn’t happen when fasting, which instead provides hormonal benefits.

Low-calorie diets, unlike our calorie approach in our 30-day challenge for sustainable weight loss, are hard and don’t work long term. You’ll feel like you’re deprived constantly and are tempted to overeat.

Fasting is simple and helps you control your hunger because it controls your hunger hormones (like leptin and ghrelin). 

As the author/philosopher Mark Twain said, “A little starvation can really do more for the average sick man than can the best medicines and the best doctors.”

Will my metabolism slow down from fasting?

No. Studies performed on a 4-day fast found that fasting maintains or even revs up metabolism as much as 12%.

Again, fasting allows your pancreas (where insulin is produced) and your body to take a rest to reset, repair, and cleanse.

Experts claim that autophagy (cell regeneration) can start as early as 18-hours into a fast, but maximum benefits are reached around 72 hours. Your metabolism levels will stabilize throughout.

Should I fast together with my partner?

Absolutely, yes! Having your partner on the same schedule as you is incredibly beneficial, as there will be fewer temptations around and more accountability and support.

I have questions. What do I do?

Leave and specific questions in the comments below, and we’ll get back to you as soon as possible and update this article accordingly.

We look forward to the discussion!

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The creators of Ryan and Alex Duo Life. We are a husband-wife duo and “lifestyle engineers.”

After eight years working in the corporate world, originally as engineers, we left our high-powered jobs to tackle our true passion — helping couples engineer their best lives.

The synergy of our engineering minds and ten years of health coaching experience produced Ryan and Alex Duo Life. Our mission is to help you transform your bodies, minds, and relationship, as a couple.

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