My 72 Hour Fast
My 72 hour fast
I just finished my 72 hour fast! I broke my fast with an avocado, easing my body back into food and wow, it tasted good!
This was my second attempt at prolonged fasting. The first was just two weeks ago, when I made it to 63 hours before deciding it was wise to stop. I had started feeling weak and a little lightheaded going up and down stairs.
Technically, I could have pushed through to the full 72 hours. I was only a few short hours from bedtime, and sleeping would have taken care of a major part of that remaining time. But I was going to be moving some heavy furniture for my wife that evening and I wanted to have as much strength as possible.
Types of Fasting
A major problem behind major diseases is insulin resistance. We often over-nourish our body by eating too frequently which leads to insulin resistance. This resistance blocks the body from getting any of the good fuel that our body needs.
Many popular diets encourage small, frequent meals with low calories. while that approach works for some people, constantly eating keeps insulin levels high, which may contribute to insulin resistance, weight gain, and chronic health issues.
Intermittent Fasting
Intermittent fasting typically means going without food for around 16–18 hours. According to many sources, intermittent fasting may support weight loss, increase mental clarity, and help regulate hormones. It creates a form of mild, short-term stress on the body, which can be beneficial in the right context.
At a certain point during a fast, your body burns through its stored glycogen (glucose chains). As glycogen is depleted, the body also releases the water stored with it often leading to a noticeable drop in water weight. Once glycogen is low, your body begins producing ketones for fuel until you eat again and insulin rises.
Prolonged Fasting
Prolonged fasting generally refers to going without food for 24 hours or more. Some people fast for 3, 5, or even 7 days. I even came across a story of someone who attempted a 40-day fast which he described as the hardest thing he had ever done. That kind of extreme fasting is far beyond what most people should even consider, and it definitely borders on the unsafe.
Prolonged fasting takes the benefits of intermittent fasting and intensifies them. Some people report that around this stage, about 87% of the body’s fuel comes from ketones. Growth hormone is said to increase dramatically, which, along with ketosis, helps the body burn fat while still supporting muscle. Many people also describe improved mental clarity, likely because ketones are an efficient fuel source for the brain.
Autophagy is the process of breaking down damaged cells and recycling them, also increases during longer fasts. This process may support cellular repair and immune function.
Summary of Theoretical Benefits of Fasting
- Increased mental sharpness
- Optimized hormones (including human growth hormone and norepinephrine)
- Weight loss
- Possible disease protection
- Increased autophagy
- Increased neurotrophic factors (which support brain health)
Potential Side Effects
- Headaches
- Mental fog
- Heartburn
- Unknown long-term effects due to limited research
All of this information comes from articles and YouTube videos, some of which may not be from credentialed sources, and I may have misunderstood or misstated some points. So take it for what it’s worth and always do your own research.
Why I Chose My 72 Hour Fast
My search for ways to strengthen and revitalize my brain naturally led me to the world of intermittent and prolonged fasting. Sure, the idea of losing some weight is appealing. I definitely need to get in better shape. But what fascinated me most were the neurological benefits.
I had tried intermittent fasting a couple of years ago when a friend introduced me to it, but I didn’t see meaningful results and slowly lost interest. These days, I still skip breakfast on work days simply because I’m busy and away from the kitchen, but I wasn’t doing it with much intention.
When I learned about the possibility of doing a 72-hour fast, the thing that caught my attention wasn’t the weight loss—it was the reported increase in BDNF (Brain-Derived Neurotrophic Factor). BDNF helps support learning, memory, and the growth of new brain cells. One video even claimed that prolonged fasting could boost BDNF by up to 400%. As someone trying to sharpen my mind, that sounded pretty amazing.
When I came across the idea of doing a 72 hour fast, I was most drawn by the neurological benefits. BDNF (Brain-Derived Neurotrophic Factor) is stimulated. BDNF helps build new brain cells and it supports better learning. One video said that BDNF can boosted by as much as 400% which as I’m trying to boost my brain is awesome.
How My 72 Hour Fast Went
First Attempt
My first attempt began after breakfast on a Saturday. I decided to eat breakfast because my company gives us a $5 meal allowance at the café, and I wasn’t about to waste it! Since I work Saturdays, staying away from food throughout the day was easy. I remember feeling genuine hunger by evening, but I powered through.
Sunday was harder, not because I felt hungry, but because I was in the living room right next to the kitchen, surrounded by the sights and smells of food. Sundays are simple in our home: we do one meal, a lunch I usually cook, and no dinner. The kids asked me to make our traditional pfannkucken (German pancakes), but I had to tell them they’d be on their own this time.
Monday morning brought our Walmart grocery delivery, which tested my resolve again. But by Monday evening, things changed—I started feeling weak, lightheaded, and winded going up and down the stairs. Since I needed to help my wife move heavy furniture the next day, I decided it was best to stop early. I had been drinking water with occasional table salt, but I didn’t have sea salt or electrolytes, and I don’t think my body was getting the minerals it needed. At that point, I resolved to try again with better preparation.
Second Attempt
My second attempt started the same way, but the challenges were different. The first hurdle came at church on Sunday during the sacrament. On my previous fast we hadn’t taken the sacrament, but this time we were. I wanted the spiritual nourishment, but I was also determined not to break my fast. That was surprisingly difficult.
Sunday night brought another major test: my daughter made a fresh batch of sticky buns, and the smell filled the whole house. I love sticky buns. I wrapped the leftovers and tucked them in the fridge, hoping they’d still be there when I finished my 72 hour fast.
Monday came with its usual grocery delivery temptation, but this time it didn’t hit as hard. My resolve was stronger.
Success
Today I waited until my stopwatch hit the full 72 hours before taking my first bite. Success! I even caught myself wondering if I could push it to Wednesday morning.
This time around, I didn’t experience the same dizziness I had the first time. I added an electrolyte solution to my water, and I believe that made a huge difference.
What I Noticed During My 72 Hour Fast
During my first attempt, I didn’t feel any mental boost at all. No sharper thinking—nothing.
But during my second fast, I actually felt mentally sharper on Sunday morning as I lay in bed, and again on Tuesday morning. It was a noticeable and surprisingly pleasant feeling.
Between the two fasts, my weight dropped from 231.8 lbs to 224.6 lbs, a pretty significant difference. During this second fast alone, I lost 4.6 lbs. I’m not sure how much of that is fat, water, or just not having food in my digestive tract, but I did my weigh-in 24 hours after my last meal.
I also checked my blood pressure before breaking the fast. I haven’t heard of any mention of effects to blood pressure, but I thought I would see if it had an effect. It was 148/80, which is much higher than my usual numbers. I’m not sure if that’s just a temporary effect of fasting or something I need to pay attention to in the future especially since I didn’t take a pre-fast reading to compare.
Conclusion
While I didn’t exactly enjoy battling temptation, I still plan on another 72 hour fast in the future even without 100% scientific proof to its effectiveness. I accomplished something hard, and that alone made me feel better about myself. I also experienced a noticeable mental boost. Whether that clarity came directly from fasting or from the mindset that came with it, I want to test it in my own life.
And of course the weight loss was pretty incredible if I can keep it off. A prolonged fast is definitely an extreme approach to weight loss, and it’s not something I’d regularly consider doing regularly solely for that purpose. But the mental benefits I hope to accompany it are what draw me back.
Thanks for reading about my 72 hour fast. Follow along with my NeuroOdyssey
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