5-7 day water fast, ketones haven't gone past 3,8 nmol/L, GKI fluctuating around 1-1.4


Hey there!

So, I’m right now in my 5th day of water only fast. Currently on 108 hours.
Mostly water, a little herbal tea in the evenings. And I have taken some electrolytes with water.
Will decide tomorrow morning if I do 7 day fast or stick with 5 days.
Feel mostly normal, but a little light headed and dizzy at times.
Mental energy and concentration is pretty good though.

I got into ketosis normally and relatively fast, on the second day measuring 1 nmmo/L and going up from there. On the 3rd day I got above 3 nmol/L. and it has stayed like this for the rest of the fast fluctuating between 3 and 3,8 nmol/L.

Blood glucose is strangely pretty high again today currently 82 mg/dL.
Yesterday it was 67 mg/dL and most of the fast it’s been in the 70s.

So my GKI on fast days 3-5 has stayed around 0,9–1.3.

The last time I did the 5-day fast I got my ketones above 6 and GKI was well below 1. So it was well into the most therapeutic range. This time somehow I cannot get my ketones more up.

Any ideas?

Am I not moving and exercising enough?
I haven’t done much exercise on this fast, just some light walking and bike commuting.
I have done a few sauna sessions in the evening.
Am I not drinking enough water?

Any other ideas what could be the factors?

I was not in ketosis before starting the fast.

Thank you guys!
Happy to come back with some results and feedback after this fast.

(Bunny) #2

When I see fluctuations in glucose like that, that’s discarded/degradated body parts being turned into glucose or catabolism. When you see ketones dropping that’s insulin responding to what’s being catabolized into glucose during the 6 different phases of autophagy and its subdivisions: Macro-Autophagy, Micro-Autophagy and Chaperone Mediated Autophagy (CMA).


[1] Autophagy includes five phases:

• initiation

• elongation

• autophagosome formation

• fusion

• autolysosome formation …More

[2] “…This process involves fusion and fission of existing mitochondria to generate new organelles and separate old ones for degradation via autophagy. Autophagy is a lysosome-dependent proteolytic pathway capable of processing cellular components, including organelles and protein aggregates. …” …More


image link


Thank you for your insight atomicspacebunny!

So, is it a good or bad thing while prolonged fasting?

I thought the aim is to have the Ketones around over 5-6 mnol/L in the end of the fast, and GKI anywhere below 1. And Glycose around 50-60 mg/dL

I normally have a pretty high non-fasting glycose 80-100 range. Or is that high?


Does this mean I’m not keto adapted even though I have Ketones over 3 mnol/L and way into 5th day in my fast?

I do feel pretty shitty occasionally.

(Bunny) #5

That looks normal to me.

Depends on your reasoning for fasting, it is not something I personally do (e.g. real, extensive 2 week fasts) all the time maybe once a year (under medical supervision) other than an occasional 3 day fast and my eating windows are pretty wide on top of that so I don’t like to push the envelope too far[1].


[1] Fasting Selectively: “…Calorie restriction refers to a chronic 20%–40% reduction in calorie intake, with meal frequency maintained [1]. Over a century of research has shown that calorie restriction reduces chronic disease and lengthens lifespan in a variety of species [53]. Since calorie restriction and fasting share many similar mechanisms and fasting often produces a decrease in calorie intake over time, the question is often raised as to whether the potential benefits of fasting are merely due to reduced calorie intake, as opposed to any particular effect of the fasting. Several studies in animals and humans have indicated that fasting may confer benefits on cell (including neuron) metabolism beyond calorie restriction. It has been shown that some mice fasted on alternate days can eat twice as much on the feeding day, such that their net weekly calorie intake remains similar to mice fed ad libitum; despite the lack of overall calorie restriction, the former still display beneficial metabolic effects compared to the latter, including improved glucose levels and insulin activity, as well as enhanced neuron resistance to a neurotoxin, kainic acid [54]. …” “…During the fasted state, the switch is “on,” theoretically upregulating autophagy and survival pathways in neurons, whereas during the fed state, the switch is “off,” emphasizing remodeling and growth pathways. Thus, unlike calorie restriction, fasting capitalizes on each sequential bioenergetic challenge by “setting the stage” for a relatively stress-free cell recovery phase; in other words, it is the switching—the intermittency—that may provide the advantage for neuron metabolism. Indeed, chronicity can be harmful, regardless of a fed or fasted metabolic state—for example, acute mTOR activation promotes muscle hypertrophy, whereas chronic activation produces atrophy [58–60], and intermittent AMPK activation enhances neuroplasticity, but sustained AMPK activation impairs it [61]. …” …More

[2] Dr. Boz GKI Chart:

image link


Thanks again for your comments!

I just measured again. I have now 4,2 nmol/L ketones and glycose 66, GKI 0.8

I’m feeling much better and actually are super productive with work.

I’m now in the second half of my 5th day. Maybe I was just slower to get the really deep ketosis going this time and there was a delay. If I feel awesome tomorrow, I’m considering to make 7 day fast this time. I’ve never done 7 days water fast. Last year I did 3 x 5-day water fasts.

I’m doing this prolonged fast for

Cognitive boost and mental clearance
See if it helps with some of my skin problems
Restart and change my eating habits
Improve metabolic parameters often accompanied by weight loss
Reduce inflammation
Gut rest
Increase autophagy
Kickstart weight loss
To test myself if I have the willpower and strength to do it


I’m in my 6th day of fasting.

Last evening and today has felt the best during this fast.

I’m now around 5.1–5,7 nmol/L ketones, 0,6 GKI, 60-70 glycose

(ben) #8

In an hour from now, I’ll be on the 7th day of my fast and I only measured a keto level of 3,0 mmol/L Glucose 3.7 (66)

Not sure why either.

I’m going to stop the fast 2 days after reaching 4,0mmol/L ketones.

(Bacon enough and time) #9

A bit more salt ought to do the trick. Don’t over-hydrate, simply drink to thirst.

(Bob M) #10

Ok, people, these numbers are meaningless. For one, the error in those instruments is terrible. Horrible. Beyond bad. I have multiple tests using three BHB meters, and each one had a different reading ranging from 0.2, 0.4, 0.8 mmol/L as an example of one test. Let me know if you want the picture. And that’s not unusual. I personally have given up using them for anything but a gross measure of whether I’m in ketosis (and even that, I’m not sure about, because 6.5 years into low carb/keto, my ketones are always below 0.5 in the morning, unless I’m fasting multiple days).

And then there’s blood sugar. Pin-prick blood sugar test meters are considered to be 100% accurate if they are within 15% of the real value. Think about that.

The only real thing I can say is that when I fast multiple days, my ketones go up and my blood sugar goes down. After 6.5 years low carb/keto, I get around 2 mmol/l after 4.5 days and blood sugar around 70-80, whereas I used to hit 4+ and low 60s for the same period.

My only explanation is that my body has become incredibly efficient at both glucose sparing and ketone usage.

An example. This morning, I did a body weight workout to failure, about 30 minutes, then went and rode my mountain bike, doing 2 minute sprints followed by 2 minutes of rest, 4 sprints total. About 1 hour total, with getting dressed for the bike, etc. That was well over an hour ago. I had only coffee with a minor amount of cream beforehand and tea with no cream afterward. I’m not hungry. At all. I now wait until I get hungry to eat after my workouts, and that’s typically 2+ hours afterward. Whereas when I first started low carb, I ate both before (usually protein/workout drink) and almost immediately afterward.

So, if anyone says “this is what should be happening to you at this time”, for anything, they are most likely wrong or basing their advice on their own physiology, which may not apply to you at all.