Why Fast? Surprising, Motivating, and Fun Benefits of Prolonged Fasting

Sweeten the Deal

Motivating someone to do a prolonged fast is like convincing a kid to go to the dentist. The long-term benefits aren’t compelling enough to do it without kicking and screaming, so we need more exciting short-term treats to sweeten the deal.

For example, for me and my first ever 3-day fast, the compelling reward was the idea of “cleaning my garage” For Kim, it was curiosity at first then peer pressure when she struggled. (Because people were following along on our Instagram stories.) For you, maybe it’ll be one of the following benefits of fasting.

These reasons for fasting change the more you do it. It gets easier and feels better. And, unlike going to the dentist, you may eventually even start looking forward to it.

In This Post on the Benefits of Fasting

Big Fat Warning:

We can’t guarantee any of these benefits of fasting. Everyone reacts differently. Factors like diet, fitness level, fatness level, genetics, time of the month, if your boss is a prick or not, whether you’re a cat or dog person, and your hairstyle will affect your experience.

This uncertainty is part of the adventure. For some, it’s another reason to fast.

And there’s always an easy fix if the fast becomes a disaster: eat.

Why Not Not Fast

dexa scans and kim lying beside them at body comp imaging
The orange stuff in Kim’s DEXA scan is fat. She’s got plenty enough for weeks of fasting before she starves.

You Might Starve to Death

While we can’t promise any of these benefits of fasting, we can promise one thing: You won’t starve to death by not eating for a few days.

For perspective, the world record for the longest fast ever is 382 days.

Here’s why you won’t starve:

The average human has 34 pounds of fat. Each pound is good for 3,500 calories, or about two days worth of food. So we’re like hikers lugging around backpacks with 68 days worth of snacks, just in case. It won’t kill us to lighten our loads by consuming a bit of it every once in a while.

More likely, it’d help.

Why Not Fast

Before getting to the benefits of fasting, let’s be realistic and safe by looking at reasons you might want to hold off on it.

To Lose Tons of Weight Immediately

As just explained, you can only expect to burn half a pound of fat a day from fasting, so if your chubby butt goes on a 5-day fast expecting to have a 6-pack after, you’re going to be disappointed.

Kim eating gelato in Spain
Jumping straight into prolonged fasting might hurt if you love sweets and snacking, like Kim.

Going Cold Turkey Sucks

If you eat a lot of processed foods and snacks all the time, your first couple of days of fasting might be rough. You may feel hangry, lethargic, brain-foggy, and even nauseous from going cold turkey on that junk.

Kim experienced this on her first three-day fast.

To avoid similar misery, wean yourself off bad eating habits before trying a prolonged fast and check out our Easy Water Fasting Tips from a Guy Who Learned the Hard Way.

You Want or Have a Baby

Prolonged fasting may have negative effects for women who are pregnant, trying to conceive, or freezing their eggs. It may not either. The science is limited and female fertility is complicated. But the safest bet is not to risk it.

For more, read this article from Whit Wellness or listen to this podcast episode from Well-Fed Women. And for more podcast recommendations for women about health, business, and life, sign-up to Just Listened‘s weekly newsletter.

You Have a Medical Condition

If you’re on medication, wait until you’re back to normal before fasting. At the very least, consult with your doctor.

Chris traveling during pretirement
I used to snack all the time until I learned about fasting in my pretirement and escaped from that habit.

You Have Serious Self-Control Issues

For many people, the self-control training is a benefit of prolonged fasting, but if you have serious doubts about your self-control and fail early on it’ll only make you feel worse.

If that’s you, start with a less-extreme goal like cutting snacking for a few days. Once that’s easy, try intermittent fasting—only eating between 12 and 8 p.m., for example. When that becomes easy, go for a prolonged fast.

You’re Susceptible to Eating Disorders

The feel-good benefits of fasting can be addictive, maybe too addictive to some.

You Have a Big Race, Presentation, or Building Ahead of You

The extra jitters some feel might affect a presentation. Pushing your body on a new source of fuel (fat instead of sugar) may be pushing it too far. And nobody wants you to get light-headed as you’re operating a crane swinging a wrecking ball at a building.

daily grateful cover image chris and kim hugging in hermanus
Kim protecting herself from my nasty fasting breath.

You Have a Hot Date

Bad breath is a common negative side effect of prolonged fasting. Mask it with mouthwash or breath mints if you must, but a) that only lasts for so long and b) it’s hard to have a hot date without food.

It’s Bad for Business

The number one reason why more people don’t fast is Big Pharma and Big Food can’t make money from people not consuming anything. No money means no Super Bowl ads pitching the benefits of fasting.

Exceptional Exceptions

A couple of noteworthy people who have made a business of telling people not to spend money on food:

  • Dr. Jason Fung. His books on fasting, The Complete Guide to Fasting, and weight loss, The Obesity Code, are easy-to-understand, motivational, and worth forking over some money for.
  • Dr. Victor Longo. When his research subjects were having a hard time sticking to the fasts he needed them to do, he devised a “fasting-mimicking diet” that allowed them to eat something and still get many of the same benefits of fasting. Then he set up a business selling this 5-day fast food package, donating his share of the profits.


Get our favorite fasting-related books, articles, and podcasts, then a new routine-breaking idea every week-ish.

Why Fast

Chris reading a fasting book, which is surprisingly unnecessary for a fast.
You don’t need to read a book on fasting to do a fast.

It’s Not Complicated

Don’t eat.

It Gets Easier and Easier

The first fast can be tough for some (like Kim), but the more you do it the easier it becomes. (I’m still working to convince Kim of this).

I honestly look forward to periodic prolonged fasts as a mind and body cleanse.

It’s Better than Free

Fasting isn’t just free; it saves you money. Few other health and sprit boosters, like working out outside, can claim the same benefit.

One of the benefits of fasting is that your brain is sharper and you can get more work done.
Kim has introduced intermittent fasting into her daily routine. It keeps her brain sharp whether she’s working at a cafe or from home.

You Get Shit Done

Firstly, fasting saves time. Less time preparing and eating food means more time for other things. It saves so much time that I sometimes wonder what to do with it when I’m fasting.

Secondly, after you overcome the sugar withdrawal stage, fasting can make you feel sharper. All the energy that’s normally used by your digestive system gets channeled to your brain and instead of running on sugar your brain will start running on ketones, brain rocket fuel, instead. For me, it feels like I’m on Adderall.

Crack Your Addiction to Food

Hunger has nothing to do with an empty stomach. It’s psychological.

That’s why you can feel just as hungry for lunch as for breakfast despite having eaten more recently.

The hormone most responsible for your hunger pangs has a fittingly goblin-esque name: ghrelin. Ghrelin comes and goes cyclically based on your daily eating routine. Fasting screws up this cycle. Screw with it enough and it stops.

No more hunger pains. No more addiction to food. You’ll enjoy eating just as much but only feel the need to do so when it’s convenient, not when ghrelin tells you to.

Pretirement cover image of Chris on the beach

Spiritual Rewards

Undoubtedly the world’s number one reason for fasting is religion. Many of the world’s religions incorporate it somehow.

It’s no coincidence. Even if you’re not religious, like Kim and me, the mind-opening, habit-challenging stimulation of fasting can have serious spiritual rewards.

Satisfy Your Curiosity

What does it feel like to not chew for a few days? Do you need to brush your teeth if you haven’t eaten anything? How does it feel when your stomach caves in as your organs shrink as they dump water and regenerate? Does the mental high of fasting really feel like being on Adderall? Do you still take shits?

Any curious person who lives by the motto, “I’ll try anything once,” needs to try fasting to get the answers for themselves.

Clean Out Your Garage

Fasting gives your poor digestive system a break. It’s been working non-stop your whole life and could use some time off. It could also use some time to clean itself out and dump the unnecessary junk that’s been accumulating over the years.

And I mean dump. Many people report unusual bowel movements later into their fasts or soon after refeeding.

Recover Better

When you’re sick, you often don’t feel hungry. That’s your body telling you to stop making it work on digesting food so it can focus on more pressing issues.

Listen up!

Kim taking a long walk on the beach in Essaouira in Morocco
When we go on adventures, like this day-long beachside walk in Morocco, we don’t worry about food anymore. Just water.

Easier Travel

When you become a master fast-er and kick your hunger addiction (a benefit of fasting we already covered), you don’t need to worry about bringing snacks with you everywhere or plan your travel schedule around mealtimes. And you don’t get hangry.

This makes fasting one of our advanced travel tips and tricks and one of our go-to ways to stay fit while traveling.

Recycle Yourself

When you fast long enough, something called autophagy happens. Autophagy is Latin for eating yourself. But unlike some lonely Hannibal Lecter, this type of self-cannibalism is good. Your body finds and feeds on the broken and old cells.

If left to accumulate and fester, these junky cells can lead to degenerative diseases like Alzheimer’s and cancer down the road. So eating them may reduce their incidence. And, since you grow new cells to replace the old ones, you’re better than ever.

It continues, too. Fasting stimulates the release of human growth hormone, which will help you continue to rejuvenate and grow even after you’re eating again.

A Desperate Last-Ditch Attempt

Many people online accounts report fasting relieved their knee pain, toothaches, bad skin, and arthritis. None of this is guaranteed and you and your doctor can probably find better solutions, but if you’re desperate, fasting may be worth a last-ditch attempt.

For instance, this guy did a 7-day water fast out of desperation because of a sore back and claims to have experienced inspiring results:

Chris and Dave about to refeed after a 5-day fast
I’ve never had a tastier cherry than these ones my friend and I ate after our 5-day fast.

Rekindle Your Love for Food

Absence makes the heart grow fonder so, for many people who do prolonged fasts, that first bite of food after days apart is unforgettably delicious.

Spread the Movement

Since no big business is going to start advertising fasting anytime soon, it’s up to us to spread the word. And the best way to do so is through our actions.

When family and friends see us fasting, they mostly think we’re crazy, but some will allow a seed of doubt or curiosity inside of them. That seed may take root and grow to the point of eventually motivating them to want to try. And if they experience some of these benefits of fasting, they too will spread the word.

Trying to understand the science behind fasting in Marrakech.
Chris reading The Longevity Diet to understand why prolonged fasting might help him live longer.

The Long-Term Benefits of Fasting

These long-term benefits of fasting are the real reason you should fast, but sometimes aren’t tangible enough to motivate many of us to do it unless we’re forced to:

  • Better blood sugar control. Basically, it trains your body to get better at clearing sugar from your bloodstream.
  • Cancer prevention and chemotherapy effectiveness. Fasting seems to cause healthy cells to protect themselves and makes carcinogenic ones more susceptible to treatments that seek to destroy them.
  • Speeds up your metabolism. This can increase your energy and lead to long-term weight-loss benefits.
  • Relieve inflammation linked to the development of neurodegenerative disorders, heart disease, cancer, and arthritis.
  • Live longer. Unlikely to be proven with randomized controlled trials, but a lot of evidence, including all the aforementioned benefits of fasting, points in that direction.

For the nitty-gritty details, this Healthline article has links to a ton of studies on these benefits of fasting:

Chris and Kim in front of the waterfalls in Tsitsikamma national park on the Garden Route in South Africa
Fasting pushed us to get out of our comfort zone and reconsider the status quo.

A First Step to a More Extraordinary Life

To live an extraordinary life, you have to do extraordinary things. (Duh.) That means pushing yourself outside of your comfort zone.

Fasting is a perfect example. Not only did prolonged fasting completely change how Kim and I thought about eating, but it also us me wondering what other habits and preconceptions we could challenge.

For some more ideas that Kim and I have found, check out the rest of our blog and sign up for our Consider This, where we share new ways to break your routine every week-ish.

A Final Question

Ask yourself this final question if you’re still uncertain or skeptical about the long-term benefits of prolonged fasting:

What’s the real downside?

Unless you face one of the serious health risks I listed under the Why Not Fast section, the worst that’ll happen is you’ll have a crappy day or two feeling hungry until you eat again.

But the upside is huge.

If your prolonged fasting experience goes well, you could feel better than ever, save yourself some time and money, and improve your eating habits for good. And if the uncertain science proves true that prolonged fasting helps you live longer and healthier, that’s just icing on the cake!

Speaking Of No Downside

See if we can’t persuade you to try, explore, or think about a different idea every week in our newsletter, Consider This.

More Fasting-ating Stuff

If you have any questions about these benefits of fasting or have your own reasons for fasting we didn’t mention, please share them in the comments!

Also, check out our other popular posts on fasting:

Disclosure: Whenever possible, we use links that earn us a cut if you pay for stuff we recommend. It costs you nothing, so we’d be crazy not to. Read our affiliate policy here.

Chris and Kim

Kim and Chris started The Unconventional Route in 2018 to share their experiences exploring extraordinary places, things, and ideas. Now, over 150,000 people a month read their questionable advice. Every week, they share a new complacency-challenging and curiosity-tickling idea in their newsletter, Consider This.

13 thoughts on “Why Fast? Surprising, Motivating, and Fun Benefits of Prolonged Fasting”

  1. Hi Kim and Chris,
    I started Fung’s 24-hour IF schedule a month ago, and cut out sugar, refined flour, and any snacking, and after 2 weeks switched to his “36-hour” (basically every second day) schedule, usually breakfast/lunch around 10:30am or whenever the urge hits, then dinner at 6ish. I am 66 years old, 6’2″, and was 265 lbs. After 3 weeks I reached 240 but then plateaued. Frustrated, I fasted for 2 days, and felt so fine that I considered extending to 3. I decided that if my morning weight had still not budged, then I would. Ît did, so I didn’t, and I am now in the 230s. Still, I was curious, so I googled 3-day fast and found your great writing on longer IF periods. My target is around 200, and I suspect slower progress from now on, but I am thinking alternate fasting days with 1 or 2 3-day fasts per month (many years of dietary sins to absolve as I move into old age!). Adding some resistance training going forward as well.
    Keep up the great work!

    • Hi Steve. 265 down to 230-something is amazing! That’s the weight of a 3-year-old! Are you feeling any better because of your new diet, too? Sounds like you’re not having too much difficulty with fasting, which is good news. Resistance training’s a good idea to keep progressing. Have you considered a DEXA scan? It could help you separate fat weight loss from muscle weight gain.
      Congrats on the continued progress. All the best.

  2. Hey great read! I’m in day 2 of my first ever water fast, Bizarre feeling but I’m positive.

    I’m drinking filtered water through a brita filter with about a teaspoon of pink salt a day spread out over my drinks.

    I’m doing the fast because I’ve not been very well recently with gut and liver/bile problems.

    I’m uncertain of how much water I should be drinking, I have a blood test tomorrow so we’ll see how that goes and if it’s not looking great I’ll just do 3 days but if it’s okay I may go for 10.

    I was thinking half a tablespoon of apple cider vinegar a day to, can I drink tea? And can I use cannabis?

    Thanks for everything guys

    • Hey Mitch. Welcome to the fast life! Bizarre but positive sounds similar to my first experience. Hopefully it’s gone well for you.

      Fasting fanatics say to only have water, but apple cider vinegar, tea, and weed are fine for most of us. My fasting tips post (and the many comments there) have more on this.

      As for how much water, that’s a good question. You can possible have too much. Drink too much and you’ll wash out some minerals you’d prefer to keep in your body. Check your urine. If it’s dark and stinky, drink more. If it’s clear, drink less. But I’m no expert so take this like your water, with some grains of salt.

  3. Ok thx for making me feel better. I have been completely fasting 3 days a week for 5 mts. Straight now . I’ve never felt better. My arthritis in my neck went away over night for real . I had the pain even went to therapy nerve test and neurologist Doctor . For 8 mts.. I have decaf Gr8 teas , decaf coffee and over 120oz. Of water if I were hungry I’ll have low sodium broth but I’m not. I have lots energy, not Cranky, great sleep, not tired . I cook for my family several days a week even fasting no problem . On barge days I eat I eat plain oatmeal made with water, apple , low fat protein, salads, plain dry Cheerios in baggy for a snack and another apple . Snack Also mixed nuts plain unsalted almonds , Brazilian nuts, walnuts . I’ve lost 33 lbs. when I lose another 7, I’ll go to fasting 2 days a week forever . My husband now joins me in Monday’s. I do have 1 cheat day a month on a special occasion. With NO guilt. I’m Assuming that’s ok . Why I decided to do this and made my own diet and I’ve tried all kinds and spent $$$$ . My #’s out high like cholesterol, border diabetes& that arthritis!!! I haven’t rechecked #’s yet. But the arthritis alone worth it .. thx. For reading letting me comment oh I’m 57 but my whole life I feel 20 ..

    • Fantastic, Judi! I should add your inspiring testimonial to the others in the post. I’m so happy you’ve managed to find a fasting routine and diet that seems to be working so well for you that you even managed to motivate your husband to join part-time. All the best with those final 7lb! And thanks for sharing your story.

  4. I’m starting a three day water fast today and was curious if the below supplements are okay to take (they’re part of my regular routine):
    Biotin (Trader Joe’s brand, 5 mg x 2)
    Psyllium Husk (now brand, 3 capsules – 5 calories per serving – twice a day) The bottle says it has no caloric effect.
    Men’s Once a Day Multi-Vitamin (Trader Joe’s brand, doesn’t even list calories)
    Other than that I’m planning to just drink: water, black coffee, green tea, club soda, and Ultima replenisher powder (once a day for electrolytes).
    Am I cheating on anything here? I started today and have only had coffee and water. I don’t want to muck this up.

    • Hey TJ. If you feel you need all of those supplements to make it through your fast and feel good, go ahead. And definitely don’t feel like you’re cheating. You’re doing way better than anyone else who’s stuffing their face with snacks throughout the day. The calories are minimal, so you’ll benefit from the “fasting experience.” Do it, see how it goes, and experiment what you can do without, or with more of, in future fasts.

  5. Hi Kim & Chris,
    I am thinking of fasting for the first time and your article really helped me in making my decision.
    Thanks a lot!
    will let you know how it goes.

    • Hi Joh Paul,
      Please do keep us posted. And speaking of posting, keep up the good work on your blog. Let us know if you have any unconventional ideas we should consider and possibly write about. Thanks!

  6. What about drinking coconut water as a cheat/hack instead of using the electrolyte powder? Has anyone reading this tried that out or would the author be able to advise on that?

    • Hi Sahsa. Coconut water has calories, about 45g per cup, most of which is sugar, so unless you only have a small amount of it, it’s not ideal for fasting. You’re better off adding calorie-free spices like cinnamon or cayenne if you want flavor, as well as some electrolytes.

  7. Goodnoon Mr Chris, It was unprecedentedly convincing article to observe water only fasting. I have been going through such articles every now and then and even decide to follow the fast but I go frail in my decision. Some or the other thing or circumstance distracts me. It was 11:26 am, Monday, 2020 when I had my last meal and took the resolution to follow Lord Jesus for 40 days. I had been an addict of chewing tobacco and even consumed other intoxicants at irregular intervals. There is the KILL THE CAN that brain washed me with its motivating posts and I quit chewing tobacco more than two years before. I have not been consuming caffine for more than 6 months. But to drive the toxins and fats both sub cutaneous and visceral from my body, I took this decision to fast without food for 40 days. I also expect some spiritual and financial breakthroughs as I came to know through the Internet. I want your support and wishes to be persist in my determination. Could I kindly expect this? It would be so kind of you. Thank you.


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