So, I am currently 60 hours into a 90 hour fast and my ketones are currently reading at .4. They haven’t gotten higher than .8. Normally by now they are in the 1+ range (I think mine average low for whatever reason! Most non fasting ketones days they average between .3 and .6). Any ideas why my ketones are so low this time round. Water and salt only.
Fasting low ketones
ctviggen
(Bob M)
#2
What’s your blood sugar? For me, these travel oppositely: as blood sugar goes down, ketones go up.
After 6+ years of low carb and 4.5+ years of fasting, though, my ketones are much lower now than they used to be. After 4.5 days of fasting when I initially started fasting, I could get 4+ mmol/l blood ketones; now, I can’t crack 2.
Camille_Yeager
(Camille Yeager)
#4
Blood sugar was 98. So not super high, maybe 10-20 points higher than I want it, but not crazy
amwassil
(Michael - When reality fails to meet expectations, the problem is not reality.)
#7
By definition, if they’re being metabolized they are not in your bloodstream and can’t be measured. One of the issues around measuring ketones is the usually false expectation that ketones ‘should be’ some fixed amount or something is wrong. Most people don’t measure frequently enough to see just how dynamic the system really is, and how much ketone concentrations vary over relatively short time spans. So-called ‘fat adaptation’ trends towards matching ketone sythesis with metabolic demand for ketones. This can result in low(er) blood numbers since not all that much is just floating around not doing much of anything. @ctviggen is quite knowledgeable about this and maybe he will make some additional relevant comments. 
ctviggen
(Bob M)
#8
Well, for me, my ketones have come down over time. It’s not anything I’m doing. For instance, my first meal of the day today was some chunks of high-stearic-acid fat with lean beef (a roast), some cheese, and some mustard. A small cup of bone broth.
My dinner will be taco meat, cheese, sour cream, salsa, maybe some onions if we have them, and maybe jalepenos if I remember to buy them. Cacao butter too.
Quite low carb, and high fat.
But yesterday my lunch as the same, but my dinner was all meat. Again, low carb.
And I can’t get higher than 0.5 mmol/l in the morning. Years ago, I would be much higher than this in the morning.
I think what happens is your body gets really good at using ketones, so they aren’t floating around as much. I just listened to this:
And Dr. Bikman says after the 20 minute point that you SHOULD have low ketones, after a while, even on a carnivore diet. He thinks high ketones at some point after becoming fat adapted are BAD, not good.
I think he’s correct. Your body will get used to using ketones, and therefore there is no need to have high level of ketones floating about.
I know people are going to come out of the woodwork and tell me that they’ve been eating 70+ percent fat on a diet (say the PKD) and their ketones are higher and therefore it’s because they decreased protein. I question this. For instance, maybe it’s ONLY the fat increase that affects ketones. Or maybe proteins only affect ketones marginally and fat affects them more. (In the tests I’ve done, I’ve still had the same amount of ketones regardless of protein level. It’s unclear what fat does to this, at least in my tests. I’ve not purposely tried to eat high fat.)
My other issue is if it’s true that eating more fat causes ketones to go up, why is this good? If you have some disease (eg, mental) or cancer, MAYBE it’s good. But for us “normal” people, I can’t see that it’s necessary. And I think it might actually be bad. (And I even question the need in cancer, as it’s blood glucose not ketones that appear to be important.)
Chantarella
#9
@ctviggen
Could this be the healing miracle for the keto rash? Maybe this is why it goes away with time? Because the only thing the doctors know for sure about the keto rash is that it is tied in with the high ketones in our blood.