How to do a Keto Fast

I have been using a ketogenic diet on and off for about a year and a half. Following a ketogenic diet; in conjunction with meal planning, I was able to lose 50lbs. I went from a peak of 245 down to 195. This past Fall I began Crossfit training at Fiverstar Crossfit. The class I attend is at 5:30 am. I was not used to waking that early nor the high intensity workouts. I needed some time to adapt my ketogenic diet to my new schedule.


I eventually acclimated, but had gained back some weight during the interim and was having trouble losing some of the excess fat. I decided to try a 3-day keto fast to try and kick start ketosis. I read a basic outline in Tools of Titans by Tim Ferriss. In an interview with Dom D’Agostino, D’Agostino details how he does his 3 day keto fast. I adopted the basic outline and tailored it to myself and what I though I had the ability to do. I knew I could make changes in the future if I wanted to try it again. After all this experiment is N=1. Here is the protocol that I followed.

How to do a Keto Fast


Starting weight: 216.5 I started my keto fast on Sunday night. I had a normal ketogenic meal for dinner. Took one scoop of KetoCaNa and went to sleep around 9:30 pm.


Wake at 4:30 am. I immediately have about 4 grams of Scivation Xtend BCAA’s since I work out in the morning. I also have my normal Bulletproof Coffee of 2x tbsp of heavy cream, 2x of Brain Octane, 2 tbsp of Kerrygold Unsalted Butter. I know many people don’t want dairy during their fasts, but I do.  I went to my Crossfit class and had an intense workout scheduled as part of the Crossfit Games Open; specifically 17.3.  This is not recommended, but it’s how the schedule of when I wanted to fast and how the Crossfit Games intersected.

After the workout I had another Bulletproof Coffee and 4 more grams of BCAA’s. Throughout the day I had 3 more servings of KetoCaNa, regular coffee, and green tea.

For dinner I made a miniature version of Bulletproof Coffee on ice. After dinner I went to bed around 8:30 pm.


Scivation Xtend BCAAs
Scivation Xtend BCAAs

Wake up at 4:30 am. Weight: 210.1. Tuesday is a repeat of Monday for the most part. My workout was much less intense though. Some things I noted were that breathing seemed easier today. I also did start to notice my mood changing for the worse. I look at my meals as ways of breaking up the day so without them my days seemed extremely long and it made me grouchy. The only hunger I felt was brought on by the smell of other people’s food rather than hunger pangs.


How to do a Keto Fast
Brain Octane

Wake up at 4:30 am. Weight 208.9. The morning was a repeat of Monday and Tuesday. By lunch time I did break my fast with some bacon and 3 eggs. My mood almost immediately shifted. I didn’t over do it at lunch nor dinner.


The next day I wanted to see how much my refeeding affected my weight, but was still at 209. A week later and I’m at 211. I had drank a ton of water during the fast so I had a good idea that the weight I was losing was fat rather than water and I believe it shows in my body composition. I was very satisfied with the results. I think a 1 day fast is something I can realistically implement once a month.


Author: David Matthews

Welcome to my site!

I started this site as a way of discussing what I’ve learned about the relationship between personal finances and physical fitness. What I have learned allowed me to lose 50lbs and improve my creditscore 150 points in the same year.

Husband. Father. West Virginia University Grad. Licensed Insurance and Financial Professional. Sports fan (Phila, WVU, and Manchester City). Huge nerd (like Magic: The Gathering huge)

3 thoughts on “How to do a Keto Fast”

  1. Interesting read. What is the financial commitment to these different supplements/food substitutes? Is it basically a wash for your portion of the grocery bill?

    1. The Brain Octane and BCAA’s are. The KetoCaNa is somewhat of a commitment but it is not something I plan on using regularly.

  2. Maybe in a future post you could tell us more about the supplements, how to use them and where to get them. How is it different using them instead of just eating keto food.

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