Low blood glucose after 4 days on keto 😞👎


I’ve been intermittent fasting for a while and was feeling pretty good, but 2 weeks ago I started keto and it’s a bit rocky. 2 days in I felt about the same as with IF, but I noticed my blood ketones had only made it up to about 0.3 even 36 hours in. As time went on, when eating I couldn’t get satiated, and kept eating and eating more of the keto food I’d made (eggs, avocado, bacon, cheese, mayonnaise in that first week). It was like my stomach had doubled in size all of a sudden.

I started running into problems with insomnia and anxiety and fatigue about 4 days in. By this time my ketones were finally up around 1.0. On the fifth night after laying awake restless and anxious until 2 in the morning I checked my blood glucose and a red light on my meter lit up saying it was low. It was at 3.6 m/mol. Not wanting to quit I toughed it out and managed to get to sleep an hour later.

The next day I checked my ketones about 3 hours after I woke up (but hadn’t eaten) and they were down to 0.7, and my glucose slightly higher at 3.8 (dawn affect maybe?)

Fast forward through another day of suffering and then I ordered a keto crust pizza from pizza 73 and ate the whole thing. I knew there were some extra carbs in the onions and green peppers but figured it would be in the allowable range. I felt so much better, and to my surprise when I checked my readings 2 hours later both my ketones AND glucose were up. This was the highest I’d seen my ketones (1.4) and my glucose was 4.2 — so still nice and low blood sugar but no more feeling crappy and no more low glucose alarm on the meter.

I had to turn the thermostat in the house down to 17 Celsius, and even then was too hot in bed without a fan on, which I’m sure must have been my metabolism kicking on.

I suppose I should mention that I’m a 35 year old male that’s a very muscular 260 pounds. I probably have about 30 to 40 pounds of fat to lose before it won’t be apparent that I’m overweight when you see me in a t shirt.

Anyways, it’s probably fair to say that my carbs were way below the allowable amount for those first 5 days, but it seems like my metabolism just shut down instead of making more ketones.

Is making sure I get a bit more carbs what I need to be doing? I’m frustrated at my low ketone levels, but even more so at the fact that my metabolism seems to be shutting down amidst shoveling down huge fatty meals without ever feeling satiated. FWIW I should also point out that I put on 2 pounds during that time, but managed to shed it within a day or two of my glorious keto pizza feast.

Any insight and tips would be super helpful!

(Bacon is better) #2

Most people don’t experience hypoglycaemia, even during the early stages of a ketogenic diet, because ketone production takes up the slack and feeds the brain in place of glucose. The common symptoms are the result of sodium deficiency (lightheadedness, dizziness, headache, and constipation; all preventable by increasing salt intake) and a loss of muscular endurance (until the skeletal muscles heal and re-adapt to fatty acid metabolism).

In your case, however, the insomnia, anxiety, and fatigue do sound like a hypoglycaemic episode. Forgive me if you already know the biology of this, but it is often worth going into. The point of a ketogenic diet is to lower insulin to the point where the liver can produce ketone bodies (ketogenesis). This means cutting the carbohydrate intake low enough to allow serum insulin to drop below the threshold, which is approximately 25 μU/dL. Above that threshold, the body is being instructed by insulin to metabolise glucose (glycolysis); below that threshold, the body metabolises fat (fatty-acid metabolism).

Because an elevated level of blood sugar is dangerous to the body, the pancreas responds by secreting insulin to drive the glucose out of the blood stream. Carbohydrate, being nothing more than glucose molecules bonded in various ways, elevates the blood sugar significantly, requiring a major insulin response. Over years of excessive glucose (carbohydrate) intake, the cells of the body start to resist the effects of insulin, and it takes more and more insulin to achieve the same response. This is called insulin-resistance, and it is the beginning of most of the chronic diseases plaguing our society.

I suspect that what happened to you is that you cut your carbohydrate intake low enough to cause problems for your brain, but not low enough for your insulin to drop low enough to promote ketogenesis. If your total carbohydrate intake is not below 20 g/day, then get it down there. If it is below 20 g/day, then you may be so insulin-resistant as to need to go even lower in order to get into ketosis. The good news is that insulin-resistance does resolve over time; the bad news is that it takes time.

So get your carbohydrate intake as low as you can, and eat a sufficient amount of protein and fat to fuel your body. See what happens. The human body has no need for carbohydrate at all, since the body can make the small amount of glucose that it absolutely requires. However, it may be that you have a problem with a hormone called glucagon, which is also involved in stimulating ketogenesis. Such problems are extremely rare, yet if you are indeed glucagon-resistant, then perhaps a ketogenic diet is not for you. So if you were to eliminate your carb intake altogether and you still had another hypoglycaemic episode, then I would advise returning to your normal high-carb diet.


Thanks for the great response! I should also mention that I’ve maintained going to the gym, so I’ve been doing about an hour of steady state cardio 5 days / week, and 3 days of weights (not much weight but I do about 20 reps until I can’t anymore x3 sets).

Since working on my diet and exercise over the past year I’ve lost 50 pounds, have adjusted well to an OMAD intermittent fasting lifestyle, and survived a couple longer term fasts such that I felt well enough to go to the gym during my extended fasts — so I was feeling like I had taken care of my insulin resistance, or at least had become much better fat adapted as my energy, mental clarity, and hunger had gotten way better.

But I’ve heard keto adaptation isn’t the same as far adaptation. Could this be it?

5 days into strict keto I actually felt about the same as my 72 hour wet fast a couple weeks earlier, except that I was feeling groggy and bloated from having a belly full of fatty food.

In both cases I noticed that I was very slow getting into ketosis, with my readings under 0.5 until about the end of day 3 and then by day 5 I had ketones around 1.5 but was having low blood glucose alarms and insomnia in both cases.

I had assumed my low blood glucose was due to having never done a 72 hour fast before, and thought having some fat and protein would take care of that — but it really seems like I might as well have just fasted those 5 days rather than done keto.

I lost the first 50 pounds in 5 months liberally eating steak and the odd veggie, and then eating a whole pizza every 3 or 4 days when I got exhausted. I was actually losing most of the weight in the day or two after the pizza binge which I thought was weird.

I’ve only lost 10 pounds in the 9 months since but I have WAY more endurance and WAY faster recovery at the gym now.

Does this sound like more of a keto adaptation vs. fat adaptation thing to you, or still a really bad insulin resistance issue?

I should also note I’ve been supplementing vitamin B, C, and cod liver oil for the last 3 months as well.

(Bacon is better) #4

Don’t overdo the exercise at the beginning. The change in diet and the re-adaptation to fatty-acid metabolism is quite a bit of stress already. As your endurance returns you should be able to return to your full exercise program. Remember also that exercise is pretty much useless for causing fat loss; its benefits lie in the realm of metabolic improvements and healing mitochondria.

This is assuming that your carb intake is low enough to keep you in ketosis. If your insulin is still high enough to keep your muscles burning glucose, the muscles compete with the brain for it, and when glucose runs low, that is the phenomenon called “bonking” or “hitting the wall,” which all those strategies for carb-loading are designed to deal with. On a ketogenic diet, an athlete is essentially bonk-proof, because even a lean athlete has thousands of calories stored as fat.

They are mostly equivalent terms, so far as I know. However, “fat-adaptation” refers specifically to cell-level changes in skeletal muscle, whereas “keto-adaptation” carries somewhat broader connotations.

In general, we advise people in the early stages of a ketogenic diet to eat three meals a day and not to fast. At the point where one finds oneself naturally cutting back to two meals a day, then one can think about whether or not to fast.

Your posts are not clear on just how long you have been eating a ketogenic diet, but slower fat loss is perfectly normal as the body approaches what it considers a healthy weight. The first 100 pounds come off much faster than the last 10. Note also that your idea of how much you’d like to weigh may differ from your body’s idea, and it is difficult to outthink two million years of evolution.

As far as supplementing is concerned, there are data to show that the body has much less need of Vitamin C on a ketogenic diet, and that it uses what little Vitamin C it takes in much more efficiently. Also, eating fresh meat is itself sufficient to prevent scurvy; you don’t need Vitamin C for that purpose.

If you are eating enough meat, you are probably getting enough of the B-complex that you don’t particularly need to supplement.

As for the cod liver oil, the challenge when eating in the USA is to avoid getting too much of the ω-6 fatty acids, not getting enough. The ω-3 and ω-6 fatty acids are essential for human life, but we don’t need very much of either, and the ω-6’s are inflammatory when over-consumed. And we want them in roughly equal amounts in the diet, because they compete for the same cell receptors. If we are eating a lot of seed oils, for instance, the ω-6’s will greatly outnumber the ω-3’s, and we won’t get enough of the latter. But it’s impossible to get enough ω-3 to compensate for overeating ω-6, so the best strategy is to drastically reduce ω-6 consumption, especially since we are then reducing the body’s inflammatory burden.

(Bob M) #5

I’d say it’s going to take you a while to fully transition into a keto diet, with that much exercise. At least a month. Easily.

And if you’re not that overweight, are muscular, and are exercising a lot, I’m not sure you have to go full-bore keto. What you’re doing now is akin to a TKD (targeted keto diet) or CKD (cyclic keto diet), and maybe you could continue with that, at least for a while? Or even keep your daily carbs higher than 20? Saw a guy on Twitter who kept his carbs at about 100g/day, still lost 80 pounds.

If you have time for a podcast, Zach Bitter is an ultramiler who eats keto a lot but also adds in carbs, depending on what his mileage is. He also has body building or other lifting guests:

You could consider some targeted carbs, at least initially.