Does a healthy ketogenic diet cause irreversible insulin resistance?


To my knowledge this has been demonstrated in mice. Mice that were not necessarily fed a healthy diet and that are mice and not as likely to eat that kind of diet like humans are in nature, for the past hundred thousand years.

However of all the studies in humans, while there have been some negative ones showing arterial stiffness or other issues, there have been none, that I know of, showing the diet to cause insulin resistance and several that showed increased insulin sensitivity.

I have read that while in ketosis one will develop insulin resistance but it is a temporary and necessary response by your body to ensure that your brain gets enough glucose and, most importantly, that this resistance is completely reversible and sensitivity will go back up if/when one started eating carbs again.

Does anyone know? Studies? Science?

(Todd Allen) #2

Blood glucose tracking can give a good sense of changing insulin resistance. If over time on the diet your fasted bg is falling and/or your post prandial bg rise to a particular food diminishes then you are likely becoming more insulin sensitive. Fasting should help.

(VLC.MD) #3

A foundational principle of low carb diets is that they lower insulin resistance in humans.


He’s talking about what’s generally referred to as “physiological insulin resistance.” I don’t know much about it, but it’s definitely a thing that can happen to some people who have been LC for a long time. Most folks who study it don’t seem to see it as a problem.
Here’s an article about it for those who want to read up.

(Take time to smell the bacon) #5

Interesting post. I note that there is a bit of discussion in the comments that “insulin resistance” isn’t really the correct term for what is happening. Also in the comments is some mention that this slow rise in serum glucose may be part of the mechanism by which cells protect themselves from reactive oxygen species.

I especially enjoyed the following passage about a German study in which the researchers “allowed mice to select their own diet and, lo and behold, the mice chose (by calories, not weight!) 82% fat and 5.6% carbohydrate. Sensible mice. (NB These German mice should each be given Professorships of Nutrition at medical schools in the most obese nations of the world. Quite what we should do with the current professors I’m not sure, but I bet the mice could think of something.)” :thumbsup: :bacon:


Paul, I’ve always had a question about physiological insulin resistance and I’m not sure if you got any insights from the article or the comments: doesn’t a higher blood sugar level present a problem in and of itself? And how do folks with higher bg - in that situation - actually have such low A1C numbers?

Calling @richard to see if he has any thoughts on this and @Zimon as well since I remember he was also looking at what seemed to be inexplicably high bg readings himself.

(Richard Morris) #7

I think a better term for physiological insulin resistance … is adaptive glucose sparing. It’s just tissue that has an option to use both glucose OR fat deciding to reduce it’ use of glucose so there is more available for the brain.

I don’t worry too much about slightly higher transient glucose if HbA1c is still low.


Thanks, Richard! It just seems like higher levels of glucose in the blood wouldn’t be great for our (tissue, organ, cell) health in general - but this is way past my level of understanding of cellular processes…



Thank you. So in your opinion this is not a problem but rather an adaptation? If so, then would it be reasonable to assume that the body can adapt back to a higher carbohydrate diet after this process and become insulin sensitive again? Are there any studies showing that this is the case? Or might we all be heading for diabetes?

It sounds like in ketosis we may end up with pre diabetic fasting blood sugar and diabetic response to high glucose meals. This sounds like the opposite of everything I have learned about ketosis.

Everything else I have read showed it helping lower peoples fasting blood sugar, increase insulin sensitivity, etc. And now this is showing the exact opposite.

Please enlighten me if possible.



Thanks and Um… crap.

or not?

It’s hard to tell.

It sounds like one will have high fasting blood sugar and high (diabetic) postprandial blood sugar (if one ate enough glucose to equal a glucose tolerance test) while in keto, that is a bad thing, right???

But that going out of keto for a mere three days will fix this and you will go back to normal blood sugar.

So… keto causes temporary diabetes now?

But 150g carbs a day (low carb compared to the standard diet most eat) will keep blood sugar levels normal and healthy. So keto is… bad?

My diet world has been turned upside down.

What am I missing here?



Thank you. What is your opinion about the article linked above? It sounds like, for all intents and purposes, ketosis causes a potentially reversible form of diabetes.



Thanks. That’s what I always thought. However the results discussed above sound like quite the opposite. A sign of insulin resistance is high fasting blood sugar, which, according to the article linked below, is exactly what ketosis causes. What is your opinion?


So the ketogenic diet has been shown to increase insulin sensitivity. This should be observable in the form of lower blood sugar. But it also causes chronic high pre diabetic blood sugar and a full on diagnosis of diabetes if given a glucose tolerance test. So it causes insulin resistance and full blown, potentially reversible, diabetes.


How can it be both???

What should non diabetic blood glucose levels look like while in keto?

I don’t think there’s any cause for alarm. LC and especially keto are fantastic for improving insulin sensitivity and reversing diabetes, and none of the information given or linked above is in contradiction to that. Once we’re super insulin sensitive and if we have long stretches of keto/vlc, some folks find that their blood glucose levels rise (a bit - not much) though their A1C stays low and their other health markers are still fantastic. “Adaptive glucose sparing” sounds like a better phrase, and I’m just hoping to understand that phenomenon a bit better.



Thank you. What about this selection of a comment by the author of the article:

"I’m presuming you’ve read Steve Cooksey? He is an example of a perfectly controlled T2 diabetic, drug free. He is fully healthy (as far as any of us can tell), but he can’t eat pizza after years of LCHF. Something changes permanently…"

So it causes chronic prediabetic blood sugar and may be irreversible. This sounds like a serious concern.

This comment conversation is also noteworthy:

"freakingout said…
I don’t know whether this post is still active. I was doing ultra low carb for 5 months (30 grams or less a day). During that time I had a FBG of 96 on a random test which gave me concern, as I’m usually in the low 80s. I quit doing ultra low carb over 3 months ago, and my fasting blood glucose is now 100-118. Post-prandial has gone as high as 162. So have I permanently made myself diabetic by this low carb diet? I would think that 3 months after going back to a more balanced diet, my glucose levels would have recovered.

5 AUG 2013, 02:47:00
freakingout said…

I was on an ultra low carb (ULC) diet for 5 months. A random blood test showed fasting blood glucose (FBG) at 96, which concerned me, as I’m usually in the low '80s. Since then, I have quit the ULC diet. I’ve been eating moderate carbs for 3 months now. Yet my FBG is now 100-120 and post-prandial can get as high as 162. Have I given myself diabetes from this ULC diet? It seems it is not reversing itself once I stopped ULC. I’m very worried that I’ve impaired my ability to eat carbs permanently.

5 AUG 2013, 02:50:00
Peter said…
Hi freakingout,

I think it is quite clear that there is zero evidence base for your having given yourself diabetes by carbohydrate restriction. The physiology is quite straight forwards, I see no reason why it should happen.

There are a stack of unknowns about your circumstances. I would be very concerned about a BG over 160mg/dl post prandially and would do whatever was needed to stop it going there. You have only two tools, LC and drugs. You need to know if you need drugs. You do need LC, on the most simplistic of generic observations…


Peter states that there is zero evidence that carbohydrate restriction can give someone diabetes. However in his article he states that one would fail a glucose tolerance test and would be diagnosed diabetic and that his fasting glucose is pre diabetic. The in the above, first comment by peter, he states that “something changes permanently” and if this “something” is a permanent insulin resistance which would presumably cause permanent high blood sugar, isn’t that very close to diabetes caused by carbohydrate restriction?

Finally, don’t prediabetic blood sugar levels and a diabetic response to a glucose tolerance test strongly contradict LC and keto improving insulin sensitivity and reversing diabetes since these are symptoms of impaired insulin sensitivity and diabetes?


One more thing, this directly contradicts the idea that LC and keto are fantastic for improving insulin sensitivity:

From the article:“Well, the first thing is that LC eating rapidly induces insulin resistance.”

I am so lost. This is the opposite of everything I have learned about keto!


Deep breath… it sounds like Steve Cooksey was a T2D and even though he’s doing great, he isn’t insulin sensitive enough to be able to handle pizza, and the answer to FreakingOut makes sense to me.

A lowcarber failing a GTT just means that they’re not used to those extreme levels of sugar hitting the system. Richard’s preferred phrase “glucose sparing” kind of answers this one.

When someone who is already insulin sensitive dramatically lowers their carb intake, the glucose sparing mechanism is more likely to kick in, and even then it doesn’t seem to be a problem (which I think is the point of his article, right?).

I’m not sure where you are health/insulin-resistance-wise, but insulin resistant folks have a very different path.

Edited to take out references to the blog post (which I haven’t actually read!!)


Thank you. Doesn’t insulin sensitivity improvement include those that are insulin resistant? The diet is supposed to improve these things for diabetics and those that are pre diabetic and/or insulin resistant as well as those with normal insulin sensitivity. Yet if the diet rapidly induces insulin resistance this is utterly impossible and contradictory.

Also there is the issue of whether or not chronic pre diabetic blood sugar levels as mentioned by the author (he said his were above 100 when fasting which is pre diabetic) is detrimental to ones health and begs the question: do they keep getting higher until one’s fasting glucose levels are straight diabetic?

(Todd Allen) #19

The temporary physiological insulin resistance of a keto diet makes sense to me. However, my personal experience differs somewhat. I had very poor post prandial blood glucose response to most carby foods before keto as well as a nearly diabetic fasting blood glucose.

After a year of keto my fasting blood glucose is healthy, ~80 mg/dl, and lately I’ve been able to eat increasing amounts of carbohydrate with post prandial blood glucose remaining below 100 mg/dl, my somewhat arbitrary target. I’m not interested in doing OGTTs to establish my degree of insulin sensitivity compared to others and am content with how this is working for me so far. I did get my fasting insulin measured and it is now quite low. Most of my gains I attribute to fasting and losing weight, especially visceral fat. Eating keto is what makes fasting possible for me.

However we are all different and your keto diet is different from mine and everyone else’s. Even if keto works for most it could still make you diabetic and destroy your health. I don’t think there is any good substitute for monitoring as best you can how your body is responding to your diet and adjusting as needed.

Also, there are many many factors known to affect insulin resistance beyond diet macros: sleep quality, chronic stress, exercise, gaining/losing fat - especially visceral fat, muscle quality and quantity, a wide variety of toxins, numerous micronutrients, therapeutic thermal stress, etc.


Yes, I think it includes especially those who are insulin resistant. Folks who are already insulin sensitive find that cycling in some carbs sometimes can be useful for various reasons, one of which might be to keep up the glucose -burning end of a flexible metabolism (? I have no idea… I’m just speculating here).

I’ve never heard of anyone getting diabetes from LC; there’s a lot that I can’t answer in detail about your questions but that - becoming diabetic from restricting carb intake - just doesn’t happen.

Here’s a question: how do we explain 100 fbg (in the blog author) but a 4.something A1c? Since the a1C is an average glucose reading over the longer term, I would take that as a very reassuring indication that the guy is not headed in a dangerous direction.

I’m pretty sure that Richard has gone into this question in depth at some point. Have you dug around the forum a bit? There’s something about this in Mark Sisson’s new keto book. I’ll type it out for you if it makes you feel better.


I hope I’m not violating some copyright laws here, but @Fry, you sound really worried. Here’s something to tide you over. Mark Sisson goes into a number of long-term strategies once someone’s spent 6 weeks or so in keto. His favorite for those who are active and metabolically healthy is in and out of ketosis, with some activity and low carb but not 100% keto all the time (where as his recommendation for those who are metabolically damaged or compromised is long-term keto).

Here’s what he says at the end of a section where he goes into a few strategies that different people sometimes use: