Portrait of sad upset young sportsman with empty bottle for water over grey background

I recently embarked on an extended water fast that would last 5 days. Water only! No coffee, juice, broth, vitamins, medicines, tasty powders, lemons, limes, salt, supplements, nothing. I have incorporated intermittent fasting into my daily routine for quite some time now. Typically, I eat in an 8 to 10-hour window and I fast the rest of the time. This is really pretty easy since all you have to do is skip breakfast, eat lunch and eat dinner before 8 pm. There are numerous researched and documented health benefits to intermittent fasting such as lowering your insulin levels, dramatically increasing your human growth hormone, kick starting cellular repair and increasing your focus and energy.


However, not eating for a few hours is pretty easy, simple in fact. Now, cutting out everything but water for 5 days, that’s 120 long hours, is a whole other story. But I had been reading and researching about the beneficial effects for a while. This is why I decided to put myself through this grueling ordeal.

Cancer and dementia are everywhere in my family. My mom, dad, cousin, uncle, aunt and others have all had cancer sometime in their life. My mother, her mother, my dad’s mother all had dementia. I am almost 50 years old and studies show I am entering the age where my family history and increasing age are priming me for both of these diseases. Especially with the family history.

Research equals inspiration and motivation

Thomas Seyfried, Ph.D., a researcher in Boston, concluded that a prolonged fast is an effective method against the prevention and growth of cancer cells. His theory is fascinating and rather than trying to explain it here, I attached the link to my resource page which includes his video. In addition to the cancer benefits, fasting has been found very effective in the prevention of dementia and Alzheimer’s disease. The link below also has a great interview with neurologist, David Perlmutter, M.D.


So, prevention of these two disease were the primary reasons I embarked on this extended water fast.


I checked my blood glucose four times per day and my blood ketones once per day. I used the Precision Xtra blood monitor so my results were very accurate. According to Dr. Seyfried, the goal of this fast is to get your Glucose to Ketone ratio (GKI) to 1 or below. The basic formula is to take your Glucose reading, divide by 18 and then divide that number by your ketone reading. On an average high carb diet, you will get a pretty high reading. If eating carbs, your average glucose reading will be around 100 and ketones will be about 0.2. That will give you a GKI of 27. Remember, goal is 1 or below to gain the therapeutic effects.

My results

Day Glucose Ketones GKI Weight (loss) lbs.
1 102 0.8 7.08 181.4
2 81 2.1 2.15 179.2 (2.2)
3 71 3.1 1.81 176.5 (5.4)
4 44 4.1 0.6 173.6 (7.8)
5 55 5.2 0.6 172 (9.4)
6 after fast 72 4.7 0.85
7 after fast 72 5.1 0.78

As you can see, it took me until day 4 to get my GKI ratio below 1. But I did witness a dramatic decrease in glucose and a dramatic increase in ketones. Also, as you can see, my weight dropped pretty significantly during the fast. It also appears that the effects continue after the fast. I am following intermittent fasting and a ketogenic diet to keep my ketones up. I also drink coffee with MCT oil to improve ketone production.

I mentioned grueling above but actually it was not that bad. Everybody at work thought I was crazy to do it and that I would die. Well, I didn’t die, which is good, and I achieved what I set out to accomplish.

My main takeaways

  1. The hardest part was psychological. My daily routine consists of coffee in the morning and eating at certain times. Drinking only water kind of messes with your daily routine.
  2. It took several days to get to a therapeutic level. This shows, for me, that I need several days to achieve these levels.
  3. The first two days are the hardest with hunger and then hunger, believe it or not, pretty much disappears.
  4. It was a lot less scary than I thought.
  5. I think it did me good in two ways: health wise and it made me appreciate food a lot more once I was able to eat again.


I will now watch to see how the benefits continue. I do plan to do an extended fast 2-3 times per year and continue my daily intermittent fasting. This was an exciting experiment and I am excited about doing it again sometime. Just not right now!

I would love to hear your fasting experiences; please email me at dan@thelowcarbleader.com to share.

If you want to hear more about this fast on The Low Carb Leader podcast, you can click on the following link.