Ketones during fasting


I have completed 48 hour fast this week and since then my appetite is greatly reduced. Last night I have woken up during the night with a very painful cramp in my calf. I am aware that this could be due to electrolytes though I felt I was being careful and took extra sodium and pink salt so this morning I took some magnesium glycinate which also contains vit b complex and vit d that. So I have eaten again after fasting of just over 24 hour as I had people staying over and it was difficult for me to say no. I had couple of pork sausages and fried egg and just a bit of vegetables on a side. The problem is I sort of feel full again but am fully aware that I have only eaten fraction of the calories that I should eat. Would you recommend to try and eat another meal before it gets dark and maybe recommence fasting after that? I don’t want to cause any damage by eating too little. I have been monitoring my Glucose and ketones to show me a bigger picture of my metabolic health and two hours post eating today my glucose was 79.3mg/dl and ketones 3.8 mmols. Since I started fasting my glucose is so stable, hardly any variation. My ketones of 3.8 mmols is the highest I ever been. I feel great, mentally and physically apart from that very first cramp in my leg and waking up in a night. Any advice would be greatly appreciated. Thank you.


If your second fast won’t be long, I wouldn’t think it’s necessarily wrong to have a smallish meal between the two but I don’t know, it’s just what sounds logical to me. And it’s what I expect from a human body considering humanity’s great experience with famine and that we are somewhat adapted to fasting even if we eat a bit now and then because survival demands to use the chance… it may be not ideal for a fast (or fast/meal/fast) if we can control things though, I don’t know but it doesn’t seem a huge problem. If one fasts for days, eats a little, fasts for days, that sounds significantly worse for me for multiple reasons but a not too long period with a smallish meal in the middle? Can’t be that bad I would think. I probably wouldn’t force eating, no matter what.
Normally I don’t like a very low-cal day but I can’t have that anyway so it’s a moot point in my own case. But if it would happen, I wouldn’t worry about it as long as my very low protein and big energy deficit lasted only for some days.

(KM) #3

potassium and magnesium are both important - your salts are basically both sodium chloride. Adding in those may help more with cramps.


Thank you. Would you take potassium supplements as well as magnesium then. I just don’t know if I get enough from my diet but wouldn’t want to overdose on potassium. Thank you.


Thank you for your advice. I’ll see how I feel later on. At the moment I don’t feel like eating but I still have quite a few hours ahead of me.

(Bob M) #6

Usually, it’s salt that’s the most important. Then magnesium. Then probably potassium. But it’s really hard to know.

I usually take more salt than anything else. LMNT electrolytes are the best I’ve tried, but they are expensive:


Thank you.


Don’t confuse stable with good, although you don’t want it shooting from floor to ceiling all the time, if you’re not giving it a reason to move, it won’t. Glucose levels transiently going up and down doesn’t equal bad, and for that, neither is Insulin. It’s just how we work. This thing happens when we do keto where we decide that blood sugar moving around and Insulin are both bad, and neither are true. It going too high (and staying high for too long) is what’s bad.

Getting your magnesium at optimal levels (always) will help a lot rather than being reactive with it, but a good electrolyte drink especially when fasting will go a long way. Since it’s harder for us to hold onto our electroyltes when we eat keto, it’s a constant thing.


Yes I agree I didn’t express myself well. I am aware that glucose will rise following a meal and gets down. What I meant was my fasting morning glucose reduced from about 5.3mmols to 4.3mmols first thing in the morning and my glucose post meal is less than 5mmols annd gets back to pre meal quite quickly. All values perfectly in range. Thank you.


Short of a particular medical condition regarding potassium, you can’t get too much. Most of us don’t get nearly enough from our food supply. I think the required daily dose is something like 4600?? I spent 8 weeks tediously tracking everything that went into my mouth to track potassium and on average I got 900 a day from what I ate/drank. My best days were only 1500 mg. So now I take an electrolyte every morning that contains 1000mg potassium. It’s not nearly enough but it’s better than it was and it does help my fasts quite a bit. It has salt and magnesium in it too.