Fast and the Curious

DISCLAIMER. The material presented here is for educational and informational purposes only. We (The Pursuit of Excellence) are not responsible for any action you take for any reason, including but not limited to any misunderstanding or misinterpretation of the information provided here. No action or inaction should be taken based solely on the contents of this information. Instead, readers should consult appropriate health professionals on any matter relating to their health and well-being.

Want to find a single antidote for high blood pressure, arthritis, migraines, chronic inflammation, and visceral belly fat? I hope you’re okay with being really hungry. Welcome to extended fasting 101.

“If physical fasting is not accompanied by mental fasting it is bound to end in hypocrisy and disaster.”  ― Mahatma Gandhi


Fasting Bio Basics.

The body breaks down carbohydrates from the foods we eat and converts them to glucose (a type of sugar that is the preferred fuel source of cells). When the body has spare glucose on hand it gets stored in the liver and muscles. Glucose in stored-form is made up of many connected glucose molecules forming what we call glycogen. The body breaks down the stored glycogen as needed to release glucose into the bloodstream for cell use.

Longer term fasting depletes glycogen stores and forces the body to adopt a different fuel source. The next fuel source in the lineup is fat. The body converts fat into ketones that the cells can then burn as fuel. When glycogen is depleted we trade out glucose (sugar) for ketones (fat). When the body is burning fat as its primary fuel source, it’s said to be in a state of ketosis. (There are many resources out there about ketosis and ketogenic diets. The important thing is understanding the switch of cell fuel sources.) But being in ketosis is a portion of what fasting has to offer.

Many find that after fasting they’ve lost muscle mass. This is primarily from atrophy. Your body will eat away at muscles for energy while fasting, but only a small amount. Why? Say you were back in the open plains of ancient times hunting an antelope. You haven’t eaten in days. You and your community could use the sustenance a hearty beast like this one provides. It wouldn’t be practical if your unplanned fast caused your body to chew up the muscle you would need to track the animal, kill it, and then haul it 5 miles back to camp. The body prefers breaking down fat and conserves necessary muscle.

Types of Fasting.

There are many different forms of fasting. Intermittent fasting, multi-day fasting, week or multi-week fasting, or in the extreme case of Angus Barbieri, a 382 day fast. For the purposes of this discussion, we’ll be covering multi-day fasts. The dominant benefits of multi-day fasts fit into these categories:

  • Immune Health
  • Cancer Prevention
  • Longevity

Immune Health.


Immune health is the most well-studied component of multi-day fasting and spearheading the campaign is Valter Longo, Ph.D. Dr. Longo and his colleagues revealed the powerful metabolic responses of 3-day water fasts in a study published in 2014. The fasting period stresses immune cells, but it’s the re-feeding period that the benefits come through.

The immune system reduces size up to 40% during the fast. After this reduction, it rebuilds stronger. This is much like muscle growth after lifting weights. During a lifting session, the muscle breaks down and reduces size. But given time to recover, the muscle returns stronger.

Subjects in the study had a higher white blood cell count (a definitive marker of immune system health) after a re-feeding period. Fast for 3-days. Refeed with healthy food sources. Upgrade your immune system.

Cancer Prevention and Mitigation.


Cancer cells are a deformed cell or the outcome from imperfect processes. Cancer cells thrive in environments with an easy fuel source. As discussed in the ‘Fasting Bio Basics’ section, that easy fuel source is glucose.

In this context, you can think of cancer cells like a dumb person. Let’s call this person Fudd. Fudd will thrive in an environment with a plentiful food source. Say Fudd lives in a 24-hour, free, all-you-can-eat buffet. If we close the buffet for a week over a holiday season, Fudd doesn’t have an easy food source to keep him alive. And because he’s dumb, he doesn’t think to just cook himself food or to venture out to find food. He dies. Don’t get sympathetic on me now. We want Fudd to die. He’s cancer!

Fasting is like closing down the buffet for Fudd. We starve the cancer cell of the easy fuel source (glucose) and the unwanted cell dies. Hooray dead cancer cells!

Won’t healthy cells starve too?! Healthy cells are more adaptable than cancer cells. Healthy cells are good at using the ketones mentioned earlier in place of glucose. The video below is a bit technical but highlights the role of glucose in cancer cells.

Dr. Longo also found that patients who completed a 3 day fast had an easier time with chemotherapy. Fasting is resiliency training for your healthy cells. This resiliency training is a stressor that the cells must endure and in doing so become more robust. Chemotherapy is also a stressor. Although the two stressors (fasting and chemo) are not the same, the resiliency component from fasting carries over to chemotherapy.

Fasting can inhibit cancer by starving cancerous cells and provides resiliency training for healthy cells to better handle the stress.


Metabolism is the chemical process your body employs to convert the food you eat into functional fuel. Your body either uses this fuel straightaway, or stores it (in body fat, muscle tissues, or the liver). The body is sensitive to errors in metabolism because it’s such a crucial component of body function. You can develop metabolic disorders due to genetics, deficiency in particular hormones or enzymes, and/or from consuming too much of certain foods.

Researchers completed a randomized clinical trial where half of the volunteers followed a fasting-mimicking diet, while the other half (the control group) kept their normal eating habits. A fasting-mimicking diet (FMD) consists of food that is not recognized by the body as food. Although the dieter is consuming food, the body behaves as though it’s being fasted. The trial lasted 3 months which compared to an 80-year lifespan (the average lifespan of an adult in the U.S.) isn’t a large enough portion to reach definitive conclusions. But there are measurable factors backing the longevity argument.

 The calorie-cutters with the highest risk for age-related illnesses saw indicators of malfunctioning metabolism decrease. These indicators include blood glucose levels, blood pressure, and total cholesterol. The fasters also experienced decrease in total body fat/waist size. Declines in all of these values highlight a metabolic improvement in the FMD followers.

The calorie-cutters experienced improved metabolic function and are likely to have a longer health-span because of it.

Attacking a 3-day Fast.

The following is the process I used to complete a 3-day water fast. The two things consumed were water and salt. That’s it.

This method is pretty straightforward. Drink water and consume 100% sea salt. I applied the listen to your body method with both ingredients. I drank when I was thirsty and consumed salt when it felt like my electrolytes were low. There was no predetermined amount of water or salt that I required myself to consume. In fact, the salt was an in-case-I-need-it ingredient. There was no time table for when to consume salt or water. Just drink when thirsty, take salt if necessary.

There are other methods which you can research yourself that include coffee, tea, lemon, and/or vitamins. However, I believe that the body has evolved to handle a strict protocol of water and salt only. It’s what your ancestors would have done 5000 years ago if food was scarce. It’s how we were adapted to operate.

During the fast, I completed a few short walks and one easy yoga session. That’s the total exercise I completed. When it comes to exercise during fasting, less is more.

The most important component of taking on a multi-day fast is to have a plan. Don’t just decide on Tuesday evening that you’re not going to eat again until the weekend. Think about the goals you’d like to get out of the fast, create a plan around that, and stick to it.

My 3-Day Fasting Log.

Day 0 – Sunday 6 pm. (0 hours. Just after the final pre-fast meal)

My mind is switching between nervous, excited, nervous….and nervous. The principle in my mind is easy. Just don’t eat and don’t drink so much water that my salts go off. I’m really wondering how I’m going to break up the day. My day is ordinarily broken up by feeding sessions. I’ll have to split it with easy walks or chatting with a friend. Not sure yet. Bring on the biological benefits!!

Day 1 – 12 pm. (18 hours)


On a normal day, I eat breakfast at 9:30 and lunch around 11:30. So I’m only 2.5 hours outside of normal, but I’m also two meals behind normal. My mental attitude is semi-weak. When my cat doesn’t get fed at her usual feeding times +/- 30 minutes. She freaks out. I feel like my cat…

I keep riding a psychological roller coaster of mental fog and mental clarity. Up and down. Up and down.

I did some rereading this morning about the benefits of fasting to serve as motivation. It seems to be working a bit, but mostly I’m thinking about food. Right now craving something greasy. A burger, some soggy french fries, and potato chips sound great! Those are not among my usual diet.

I guessed cravings for cakes, candy, and ice cream would be insatiable. But they honestly sound terrible. Like worse than nothing terrible. I’ll just keep fantasizing about deep fried butter.

Day 1 – 8 pm. (26 hours)

Feeling good now! I watched my wife eat dinner. Not like a creeper drooling from the corner of the room. But she was eating and I was there. Sipping my water. I expected to be jealous or feel some kind of desire for dinner. Not the case.

I’m thinking there is a link between my normal eating times and hunger sensations. Normally I’m done with dinner by 6:30-7 and as soon as it was 7:00, my hunger subsided. The psychological roller coaster of fogginess and clarity has persisted all day. Hoping that diminishes tomorrow.

Day 2 – 12pm. (42 hours)


I don’t feel hungry so far today which is good, but super weird. Still feel a bit strange mentally and physically pretty weak. I kind of expected more of a breakthrough at this point, but so far just feel blah and ready for some food… even though I’m not hungry.

Last night I had at least three dreams about food. My dreams varied, but the sequence was the same. I had just finished eating a huge meal and then was pissed because I’d forgotten about the fast. But man did that food sound delicious. Luckily, the fast is still going strong even if I feel partially defeated.

Hoping the rest of the day picks up and that I can get some momentum going.

Day 2 – 8 pm. (50 hours)

My hunger subsided again after 7 pm or so. I’m hoping to channel that “I’m outside normal feeding hours” mentality into tomorrow to feel good all day.

Day 3 – 12pm. (66 hours)


Feeling tired today and am obsessed with thoughts of food. Right now any and all food sounds good. I haven’t been able to channel that “I’m outside normal feeding hours” mentality. The struggle is real! Hunger be damned, I’m determined to push through and get the full 3-day-fast benefits.

I’ve also been very concerned about the effects of Hurricane Harvey. Many family members I’ve got are feeling the effects of the flooding. Parents are stuck in their neighborhood, luckily with power most of the time, food, and clean water. Some of my extended family has had flooding in their home and some have been spared. Overall, it’s been tough feeling helpless. It’s also strange to think that the very thing that is keeping me alive these past few days…water…is killing people in a city I grew up in. It’s the strongest connection I’ve got with them.

As challenging as it sounds now, I will do a bit of a tapered refeeding to reawaken my digestive system. I’m going to start with some tea. Then a juice (mostly vegetables). Followed by some bone broth and then likely something I find easily digestible (likely eggs and some spinach). Then for dinner, I’m planning on eating slowly but not restricting quantity. Leaning towards fish taco bowl!

Day 4 refeeding.

Did not sleep well last night, but didn’t really care. Refeeding day!

I was able to start slow but ramped up a little quicker than I’d planned. I did have a cup of tea and waited about 30min. Then I made a Green Superfood drink and again waited about 30 min. Then I had some bone broth followed by some almond butter. I decided to wait a couple of hours after my first solid food.

2 hours later, my body felt fine and I still felt hungry so I went for full lunch. I headed to Whole Foods and went to town on the salad bar. It was one of the best meals I’ve ever had! The sun was shining, the birds were chirping, and my digestive juices were working. It’s making my tongue sweat just thinking about it. I expected this large meal to cause some negative repercussions, but it seems my body is well adapted to the refeeding process. Bring on the food!


I ended up having a mish mosh dinner. Olives, cheese, nuts, almond butter, shredded coconut, leftover roasted veggies, carrots, and hummus. My stomach felt physically full, but my body was asking for more. I stopped eating though. No need to bust a gut!

Personal Fast Conclusion.

I’m hopeful that I will feel some benefits from this fast in the coming weeks. If I sense zero physical benefits, I feel really proud for having completed this. I ended up going 84 hours without food. Not an easy task!

Many people around the globe starve for days at a time without choosing to do so. It’s part of life. This is one of those things that cannot be put into words. You won’t fully understand unless you experience it yourself. It’s much more humbling than I expected.

My mind wants to tell me that other people (maybe with larger fat stores or slower metabolism) may have an easier time of it. But honestly, I don’t know. And I don’t think we can know. Your individual experience is just that, your experience. What I do know is that anyone who takes on a fast of any length is a serious badass.

Final Notes.

Studies show that multi-day fasting can offer incredible benefits. From immune boosting and cancer prevention to upgraded metabolic function. Human evolution has involved much fasting (frequently called starvation) and our bodies should be able to handle the pressure but proceed with caution.

If you’ve completed a fast of any type (water fast, juice cleanse, modified fast, etc.) or if you’re thinking about taking on a fast, I’d love to hear about it! Leave a comment below and tell me how your fast went or what you’re hoping to take on!


Further Reading:

The Complete Guide to Fasting: Heal Your Body Through Intermittent, Alternate-Day, and Extended Fasting by Jimmy Moore and Dr. Jason Fung

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