Ketogenic and thinking


Don’t take it the wrong way, I don’t try to offend anyone. I’m just a bit curious and would love if you enlighten me up.

From what I read, your brain could only receive energy from carbs. So when people go ketogenic and lower massively they carbs, where they get the energy for thinking?

I’m not trying to say that they don’t use the brain or don’t think much. I’m just wondering how it works.


During ketosis the liver uses fat to produce chemicals called ketone bodies, which can provide energy to many types of tissues which would otherwise take glucose. The brain can adapt to get about 75% of its energy from ketone bodies. The remaining 25% must come from glucose. If the person is still ingesting a little bit of carbs, these will mostly go to the brain. If they aren’t ingesting enough carbs to meet the brain’s needs, the liver will transform protein into glucose through a process called gluconeogenesis.

Anecdotally some people report feeling tired and mentally sluggish when in ketosis, while other people report that they actually feel more alert and mentally acute. I don’t think anybody really knows why that would happen.


Thank you.
It’s amazing how the body adapts to different situations.

I suppose that puts an extra stress on the liver, so what are the benefits of ketosis?


I suppose it must put stress on the liver. I don’t think there are any known benefits of ketosis which exist according to scientific consensus, outside of its medical benefits for some epileptics, etc. For something on the “pro-ketosis” side of the issue, but very rigorous, you might read Peter Attia’s treatment of ketosis. Very interesting stuff.


Some say that ketones are a more effective form of fuel for the brain. You can believe it or not. People on nutritional ketosis usually report being more energetic and having more mental clarity.
The fact that the body dont make ketones if glucose is abundant dont mean that glucose is a better fuel either.

Being a fat burner has some other benefits.

You dont have to worry about insulin spikes, sugar crashes, or something similar.
You are less dependant on the time and frequency of your meals. If you eat more carbs than needed, some of them are transformed into a less available chemical form (if you are geared to burn carbs). If you eat more fats than needed, they are just stored awaiting to be used.
If you decide to cut calories you dont put extra stress on the cells because they already are geared to metabolice fat. On a high carb diet you do.

Being honest, these are benefits of a low-carb fat-burning diet, not necessarily keto.

Surely making ketones put some extra stress on the liver. But on the other hand a glucose burning diet puts extra stress on the pancreas and nobody seem to care.

The tiredness and mental impairment that some relates to a keto diet is believed to be caused by a major lack of electrolites. High carb diets promotes liquid retention, low carb/keto ones dont. When one goes from a high carb diet to a keto diet a lot of liquid is lost, and this causes a massive electrolites and minerals loss. Taking extra supplementation during the adaptation phase seems to alleviate it.


Can you back that with links?



Is called “keto flu”, or “low-carb flu”.


I’m seriously thinking of going keto to avoid the crashes that come from eating carbs. Thanks for the help!


I’m speaking from ignorance, but I wonder if that difference is from the ketones. Most peoples don’t have a good nutrition before starting special diets. If that is the case, when they start a ketogenic diet they start eating more properly with a lot more of nutrients, hence the more energy and metal clarity.

Just an idea.

The only difference I personally see between a ketogenic or carb diet:

  • Carbs are quicker to digest and, if you use simple ones, give peaks of energy and then you feel hunger. Of course you could avoid the peaks if you use complex carbs.

  • On the other side ketogenic diet digest slowly and provide continuous levels of energy, and don’t make you hungry so often. It make the liver work more (which doesn’t mean anything, from what we know it could actually be helpful and prevent some problems).

So it all comes down to preferences and your stile of life. If you prefer a lot a small meals or have few big meals.


One apparent advantage of a ketogenic diet is the steady “flow” of energy. That alone should make it very worth it.


This seems like a highly plausible explanation. Thanks for the idea!


You can do that with carbs too. One way is having lots of small meals, other way is eating polysaccharides which have very long chains (as Rob explains) and hence take more time to digest, giving a steady flow also.


Nope to this particular one.


The more I read about the ketosis effect the more I get interested, trepidatious as I am (took me a couple months before starting on Soylent.)

I’m pretty sure I’m at a more stable point with my formula and general intake, so I might give this a shot for a week or two (after this next month of chaos has died down) and see if there’s much of a difference.


An overall better nutrition surely can result in an improvement, but I don’t think it is the sole responsible.

Fasts and ketogenic diets have a major point in common: they make the body enter in a prolonged state of ketosis. People who do fasts report similar wellbeing feelings, and in this case the better nutrition hypothesis is not applicable. It can be the benefits of the “detox” aspect of fasting (which share some similarities with the “keto-flu”, btw) too, if you buy into it.

The constant release of energy can be the key here. If one cuts the “low” times the mean performance increases. Probably this is even more important during the night, as usually the longer span between meals are the sleep hours. And a better sleep is very important for a good mental (and physical) performance.

Maybe ketones aren’t a better fuel by themself, just a more reliable one.


How do you explain people who suffer from mental illnesses or epilepsy and who improve considerably while under keto but not when they’re medically out?


What do you mean with “medically out”?
I don’t know why, but it seems that probably the ketones have some anticonvulsant properties.


Or, that glucose (or what the brain would use outside of ketosis) has a higher chance of causing convulsions than ketones.


Your brain only uses glucose. Ketosis is effectively your brain turning fat into glucose.


I can only speak from my experiences on Atkins, but for me here are the benefits from being in Ketosis (AFTER the induction a.k.a. detox phase) were:

  1. Sinus headaches disappeared.
  2. Joint pain disappeared.
  3. In general, all inflammation disappeared.
  4. I began sleeping through the night and waking refreshed instead of still tired.
  5. My allergies either disappeared or for whatever reason stopped bugging me.
  6. My cholesterol overall dropped and HDL & triglycerides improved. (LDL didn’t move but wasn’t horrible to begin with - I started at around 199 total and only went down to around 180 - don’t recall the specifics tho this was 10 years ago now lol)
  7. I did eventually start feeling VERY focused but it took about a month or 2. This was notably when I crossed the 45 grams of carbs per day threshold. Under 45 grams and I still felt a little foggy. Not sure if this was the reason or if my body just took that long to adjust but I was well into OWL at the time this began. More on the Atkins phases.
  8. Around the same time I began having absolute buttloads of energy. As in I felt, LITERALLY, like a kid again. I could not even sit still for a 30 minute tv show. I was up at every single commercial to do SOMEthing. As a result my home was completely immaculate LOL.
  9. I was able to drop enough weight to start exercising daily without pain.
  10. Once I added the exercise, my energy level got even crazier and sometimes even made my 7 year old daughter tired from watching me instead of the other way round!!

Anyhow I have never ever EVER felt better in my entire life than when I was on Atkins. Things I feel are important to note here:

  1. I did Atkins RIGHT. Meaning I followed the book precisely and did not do a bastardized version of it. (2nd edition version prior to all the sugar alcohol acceptance nonsense) I kept up my water intake and started excercising as soon as I was able. I rarely cheated and ate my salad every day (but I did cheat on occasion LOL I’d be lying if i said i didn’t!).
  2. I’m an O+ blood type. Check out the book Eat Right 4 Your Type - it really explains a lot and gives some very good clues as to why Atkins seemed to work so well for me personally and I’m quite convinced they’re related. I’m betting blood types other than O’s though probably find Atkins and other low-carb diets not as beneficial for them, and since most of the world’s population is an O type it’s also probably why the high carb infested diets including with all the processed carb junk we have today are resulting in soooo many overweight individuals… but, that’s just my opinion i have nothing to back that up with.

Anyhow so that’s my take on it and I’m definitely all for Atkins for any O type who needs to lose weight and then move into the lifetime maintenance. My story - i got preggers and lazy and poor. The bad thing is that it does cost a lot more to not eat any processed crap!!