My Potential Cancer Risk Reduction Multi-Day Fast Version 2.0

It’s about time for me to ramp up my second week long fasts. I developed this for my own needs and did the first try of it back in July, as documented here . For this second round I’m going to be tweaking some things based on lessons learned from my first attempt. Below I’ll outline everything again and the changes I’m making to it.

The usual disclaimer applies: I am not a doctor, trainer, dietitian, nutritionist, or any other expert in any related field. I’m talking about my amateur and anecdotal experiences here and none of this should replace expert medical advice.


As I’ve written before , fasting has come and gone in popularity over time and when it is on the upswing its promises are often ludicrous to dangerous. That isn’t to say it has no potential benefits, it’s just no miracle cure. Based on the writings of Valter Longo and the research he and others have done I’ve honed in on one of the potential fasting benefits that is applicable to me: reducing the risk of cancer. My write ups last year highlight the ins and outs of that. But the TL;DR is that being in a severe nutrient austerity mode hypothetically triggers cellular autophagy, reduced body fat, and changes in other markers that hypothetically can reduce the risk of getting cancer. Because I am in good health, know I get more than sufficient nutrition, know how my body handles fasting for one or multiple days, meticulously track my biomarkers, and I know the biggest pitfalls of fasting, I am comfortable doing this one week “cancer” avoidance fasting protocol I’ve created for myself. The core is a three day “water” fast with a transition in and out day.

Preparation for the Fast

As I stated in my “Thoughts on Fasting” post, one should make sure they are in good physical health and ready to do a multiday fast. That means having seen your doctor recently and had blood work and have successfully worked up to at least a full day of fasting. A more immediate preparation step for the fast would be to eat really healthy for a good week leading up to the fast and tracking your nutrition in something like Cronometer to get a sense of where your nutrient levels are on a regular basis, how much water you are consuming and where/when that water is coming from. I also specifically recommend making sure to take multivitamins for the weeks leading up to the fast to ensure that you have more than adequate B1 (Thiamine) levels.

The Fasting Plan

The performance of this fast takes a total of five days:

  • Day 1 (Transition In Day): The transition in day should be an 1100 calorie diet with a macronutrient profile of about 500 calories from carbohydrates, 500 calories from healthy fats, and about 100 calories from protein. Along with the standard foods a high quality multivitamin will be taken. The last calorie consumption should be no later than 7 pm. The remainder of the evening one can consume calorie-free beverages. I will be meeting these levels by eating this soup recipe designed specifically for this fast plus two ounces of raw cashews, and my usual multivitamins.
  • Days 2 - 4 (Fasting Days): On fasting days one should be sure to stay hydrated with non-caloric beverages. This can include things like seltzer water, coffee, tea, etc. Things like coffee and tea cannot have any sugar or creamers added to them. In order to help mitigate electrolyte imbalance issues one can use electrolyte packages like LMNT Raw Unflavored Electrolyte Packets . Optionally, if it helps with staying power a couple of cups, less than 50 calories, of vegetable broth can be used instead of electrolyte packets.
  • Day 5 (Transition Out Day): This day will begin with a cup of broth at 9 am. Two to three hours later, at late morning or lunch time, a cup of healthy vegetable soup will be consumed. This will be the exact same soup recipe used on Day 1. If eating goes well then I will snack on the soup throughout the day as well as eating a “full portion” size by mid-afternoon and a “full portion” size as dinner. A multivitamin will be taken as well. The macronutrient profile for the day should be 800 calories with most of that being an approximately equal balance of carbs and fats. Minimal protein should be consumed.
  • Day 6 (First Post Fast Day): No calorie restriction or macronutriet ratios but following the FMD’s exit day criteria of a diet rich in complex carbohydrates (veggies, fruit, rice, and past/bread/grains preferrably of the whole grain variet). A minimal amount of fish, meat, and dairy should be consumed as well.

Assuming that one keeps with the eating schedule specified on the transition days this creates a total fasting duration of 86 hours or just over 3.5 days. If one eats dinner a few hours earlier and doesn’t eat until lunchtime on the transition day that can extend to 3.75 days.

Along with the mentioned diet parameters above I’m also going to be ensuring that I get adequate movement throughout. Each day I will do body weight exercises/calisthenics to keep my muscles stimulated. These should not be exercises hard enough to cause muscle breakdown. This is just about maintainence to reduce atrophy. I will also do my usual 30 minutes of cardiovascular work but I will do it at extremely light levels (Heart Rate Zone 1 and low resistence levels on the bike or elliptical machine). Basically I should barely break a sweat doing any of these exercises.

Lastly I will be taking my blood pressure throughout each day as well as monitoring heart rate to ensure everything is staying within normal parameters.

Differences from Version 1.0

This plan on the surface looks identical to the original fast I did in July. There are some subtle differences. While I do take multivitamins all the time and on the two transition days, I didn’t specify them in the original version. Because the B1 (Thiamine) deficiency is a potential problem with refeeding I wanted to spell that out specifically. In the original version on the transition out day I ended up nursing the soup throughout the day leaving the same full sized serving I had on the transition day for dinner. While eating six cups of soup was not a problem for me before the fast it was uncomfortable to do at the end. I therefore want to limit the “dinner” portion to 3-4 cups by eating a larger portion throughout the day along with the snacking. The last change is that while I did do exercises during the first phase it was mostly light walking and light yoga. I experienced a lot more muscle loss during the fast than I wanted to. I therefore want to ramp up the muscle stimulation a bit more but not too much. I think this current proposed level will strike the right balance on that.


The implementation of the above should be pretty straight forward. I have some planned travel that is happening around this that will make the transition out more complicated. Essentially Day 6 which is supposed to be unrestricted but eat mostly complex carbs with a minimum of fish, meat, and dairy, may not be in the cards since I’ll be traveling all day and going to a party where I’ll probably indulge in some goodies. Granted that will be towards the end of the day so maybe I can keep things in a reasonable range anyway.