Last week I stopped eating for three days. I love eating and I love food, but I felt I had no choice. I had to stop for 72 hours. Staying healthy takes more than eating well and exercise. Before modern times, fasting (not eating for long periods of time) was often necessary. Food was scarce. Not anymore. But, we can still enjoy the health benefits.
Benefits of Not Eating
What makes fasting healthy is multi-faceted and not strictly proven in humans. However, there is a glut of proxy evidence (mostly in mice) that points to likely benefits. To be honest, I take the same approach to everything in life: if it hurts a little bit, it's probably good for you. Exercise, relationships, and learning all hurt a little bit and are good for you.
Let's break down the benefits into five key areas.
Blood stem cell regeneration has been shown to improve with fasting, peaking at 72 hours. A health immune system is based in healthy blood, include white blood cells. See https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4102383/ for details.
It is true that your immune system becomes weakened temporarily, but each time you do a long fast it becomes stronger after. Keep that in mind while you are fasting - wash your hands often!
GH triggers building and repairing healthy tissue, in both the body and brain. It not only means building muscle and brain cells, but also fixing "broken" cells which is essentially "anti-aging". See https://thefastingmethod.com/fasting-and-growth-hormone-physiology-part-3/ for details.
Many people are concerned that fasting burns muscle, but if you think about it logically, why would that happen? Muscle keeps us healthy, active, and surviving, which becomes more critical when we can't find food. You must stay strong to seek out plants and animals to eat!
Change is the only constant (🥁), which is also true for cells in the body. They are constantly dying and being born. Some cells are poorly made or get damaged. That's where autophagy comes in. Those cells are destroyed so they don't slow down processes or turn into cancer. It is also a recycling action, which is partially why we retain lean mass during fasting. New cells are created using the old cells - the protein is reused.
It is unclear at what point autophagy happens, but the research points to the peak benefits at 72 hours (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3106288/).
This is the first area so far where even longer fasts are even better. Ketones are generated from burning fat as fuel, which breaks down into energy (acetyl-CoA) by both the liver and the brain. Ketones are a more efficient form of fuel for the brain, which is why a lot of people experience a clearer head when fasting.
If you keep fasting, you will generate a higher rate of ketones. This is result of why everyone is so nuts over fasting - it CAN help lose a lot of fat. See https://www.climbingnutrition.com/diet/a-ketosis-biochemistry-primer/ for a deeper dive on the biochemistry.
Blood Glucose & Insulin
Arguably the most important aspect of any fasting regimen. You might think taking care of your glucose and insulin is only valid in diabetic and pre-diabetic patients. We should all be aware of our metabolic fitness so we can AVOID those conditions. Fasting is an unmatched treatment in this area.
Fasting keeps glucose and insulin levels low and relatively constant. Why is that important? Spikes in these creates inflammation, which causes aging. Worse, even if you don't gain any weight, swings in insulin causes insulin resistance (IR). Extreme IR is essentially what type 2 diabetes is. Basically, the energy absorption and use system in the body breaks.
Not only is this incredibly important system broken, but it impacts almost every other biological process. Brain energy and clarity is diminished. Immune health declines. Sleep suffers. Irritability. Obesity. Constant hunger. These are all symptoms of insulin resistance.
This is probably the most known and understood health benefit of fasting. There is no question. If you practice fasting, you will improve your metabolic fitness, reduce insulin resistance, and improve your health because of it.
Case Study: Me
Here's what I experienced during this fast. I'm not going to leave anything out - good nor bad.
I've been practicing a 16:8 intermittent fasting protocol for about five years, which made it easy for me to transition to longer fasts. My previous long fasts (36-60 hours) have been difficult. The 36 hour fast I tried was without coffee (of which I'm addicted), so I went into withdrawals at about hour 30. I felt like I was going to die. I drank as much water as I could stomach and some decaf (which has a tiny bit of caffeine) and I was fine an hour or so later.
The three days before my fast I ate a very clean diet. Whole foods, high protein, no alcohol. I got plenty of sleep and drank plenty of water. I love high intensity exercise because it gives me a mental high, which I kept doing up until the fast. Rowing, kettlebell, med ball, bodyweight are my standard methods.
In the past it has been difficult for me to keep fasting because I'm the family cook and my son eats almost constantly. To do my best to avoid breaking my fast early, I scheduled it during the days of the week when I didn't need to cook as much and be around people eating. This a necessity until the fasting muscle is strong!
Start @ 1pm on Wednesday
End @ 1pm on Saturday
To start the fast off well, I wanted to stuff myself with nutrition. I was able to get my full day of food within 6 hours...just barely.
The fast started about 1:15. The rest of the day was easy; I stayed full all day. Slept great.
It was a bit of a struggle drinking black coffee because I usually drink it with half & half. The second cup went much better because I decided I was going to enjoy it. A positive mindset makes a huge difference.
Starting on this day, I canceled all my HIIT workouts and stuck only to walking. 10,000 steps each day.
In the afternoon, I began to feel an upgrade to my mindset and mental energy. I didn't realize it until the next day when it continued.
The entire day was like a dream. It has been a very long time since I felt like everything was on point.
In the movie Limitless, Eddie's girlfriend broke up with him due to his lack of motivation, ambition, and focus. The moment he took NZT-48, everything cleared up and his brain worked at levels 10x than he was used to.
That's basically how I felt from Thursday afternoon to Saturday morning. However, the fast wasn't the main driver as I figured out - I'll go into that in the summary.
Mid-morning was the only point when I was looking at the clock waiting for 1:15pm. I was ready. My body was ready for some fuel and nutrients. My limitless energy had worn off.
I broke my fast with my daily dose of "boilerplate" - a mixture of pork sausage and veggies covered in half a dozen eggs, avocado, and hot sauce.
Stretching yourself is the only way to grow. I can say without a doubt I grew during this fast, especially in my mental fortitude and energy.
The only way of sticking to something difficult is having a strong, personal reason that makes it easy to commit. I told a few people I know what I was up to, so if I didn't get it done, what would I be? A liar? Something like that. I take pride in my discipline and my reliability, so it would have hurt.
All I consumed over the 72 hours was water, black coffee, turmeric ginger tea, and supplements (fish oil, vitamin D).
It took me a few days, but I found a proper explanation for my "limitless" feeling, which came back after I broke my fast. I began eating nutritional yeast, which is rich in vitamin B2, B6, and B12. It boosted my ability to create energy more efficiently, in my brain and body. Fasting probably increased the feeling a bit.
Why Not Fast
Extended fasts are not for weight loss, they are for health gain. Doing periodic extended fasts will help you lose fat if you combine them with a healthy lifestyle, but they are not a quick weight loss hack.
It takes commitment. If you aren't able to adjust your environment to enable success, it will be difficult and makes for likely failure. Change what's happening around you to help you be successful first. Get your family on board. Make a plan.
The other issue is hormones. Ghrelin is the hormone that causes the hunger feeling; telling you to eat. It is on a schedule. You must push through that. It will go away and adjust to your new schedule.
My next 72 hour fast will be in May. Between now and then I'll be experimenting on myself with anything that makes sense to try. Nutritional yeast was one of those things. What will be the next one that changes my life?
Twitter is where I hang out, so follow me there as I continue to document my journey.