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Comment by mrandish | Hacker News Reader

It's only N=1 anecdata but since going to a VLC/Keto diet I've felt cognitively sharper (in addition to other benefits like losing weight, needing less sleep, etc).

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I was keto for six months a year or so ago and definitely felt sharper at the time as well. Turns out I like carbs more than clear headedness

Same story for me, also went keto for approx. six months and experienced the same benefits but once I started carbs again, those seemingly great benefits loose against the ease of just being able to eat "normally".

You can get the same effect with much less lifestyle disruption just by exercising. Specifically low intensity cardio trains your body to metabolize fat efficiently.

What does metabolizing fat have to do with carbs giving you brain fog?

The brain fog is caused by rapid fluctuations of blood sugar. Low intensity aerobic exercise has a number of positive effects that all play off each other: You metabolize fat more readily as an energy source, which makes your body less reliant on carbs. This alleviates the exhaustion you might normally feel as your blood sugar crashes. And carbs (and especially refined sugars) are routed directly to muscles, blunting the insulin response and increasing insulin sensitivity.

It doesn't. That's why "Hungerast", i.e. sudden loose of energy due to all carbohydrates being used up is a thing in all endurance focused sports.

It's actually not a thing in "all" endurance sports. Once you push into the realm of ultra endurance, athlete become so efficient at fat metabolism that they never "hit the wall" so to speak.

I've read that keto diets cause brain fog. I searched it quickly and a bunch of results turned up, too.

Is keto intended to be a long term diet?

Some would say keto is a way of eating as opposed to a diet that can been seen as a temporary change of eating habits.

I've never heard anybody say that keto causes brain fog. In fact a lot of people describes the opposite result which I would think most search results are about. There's also something called "keto flu" which some people experience for some time when they switch to a keto diet.

These terms are pretty vague and the best way to get a better understanding is too try keto yourself. It's just a different way if eating. You don't have to cook fancy meals and you can stop at any time.

I did keto for 5 months or so back in 2014. I found the brain fog description very apt. I couldn't think beyond a couple of moves ahead, which began affecting my work. Going back to a normal diet I was fine again.

I believe it's very much a person to person thing, I typically feel much clearer on a keto/low carb diet.

You do yourself.

If "normal" diet works, keep on it. Cheers.

I’m 4 years into carbohydrate recovery and strict keto. I expect to live the rest of my life this way. I have not experienced brain fog after my first few weeks of withdrawal.

The answer is: it depends.

The first two weeks while the body adapts, can have worse things than brain fog, and they are known as the keto flu.

Some people can suffer from it, others are just fine all the time.

After your body adjusts, you can feel sharper for a longer time than in carb heavy diets.

In my particular case: I used to work fine for about two or even three hours after lunch (getting my carbs to be able to work).

Now, with a keto diet, I can work for eight hours straight. I am and feel sharper. I have been in Keto for years now.

If you're having trouble concentrating on a ketogenic diet it's likely that you're not eating enough vegetables, and might be eating too much protein.

Too much protein can take you out of ketosis, but people think they can just eat lean hamburger three times a day.

If the fat/protein ratio is right, the inability to focus can be a symptom of electrolyte deficiency, particularly sodium, potassium, and magnesium. You should be getting potassium and magnesium from vegetables, but supplements can be a useful diagnostic tool: If you take 400 mg of potassium and find, an hour later, that you're thinking more clearly, that's data.

Don't overdo it with electrolyte supplements, though; too much sodium can increase the calcium in your blood enough to give you kidney stones, if you're lucky, and worse effects if you're unlucky. Too much potassium can mess with your heart.

Eating more protein doesn't take you out of ketosis, that's just a myth; it will just lower the amount of keytones that are being produced. If only are protein or nothing at all and you would still be in ketosis.

Keto diets are usually (not always!) used to lose weight.

Calorie restriction is a sure way to get brain fogs, and it's easy to inadvertently be in caloric deficit when on keto, because you have to give up many foods, and there are no sudden cravings for sugary/starchy food.

The problem with keto is, just like with "normal" diets is the wildly different formulations.

You can do keto with trash food or simply bad ingredients (e.g. vegetable oils for fat, various processed "keto snacks") and aside from maybe some weight loss you won't experience any of the real and sustainable benefits.

This is why you can't go with people's testimonials, I can guarantee you that people who say keto didn't work for them simply didn't know how to formulate the diet properly.

> Is keto intended to be a long term diet?

According to the literature, I would definitely advise against it.

Good summary:

https://www.thepaleomom.com/adverse-reactions-to-ketogenic-d...

Higher all-cause mortality:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3555979/

Growth retardation:

https://www.sciencedirect.com/science/article/abs/pii/S00028...

https://www.sciencedirect.com/science/article/abs/pii/S02615...

https://pubmed.ncbi.nlm.nih.gov/12455855/

https://pubmed.ncbi.nlm.nih.gov/18676520/

Kidney Stones in children:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2852806/

https://pubmed.ncbi.nlm.nih.gov/11095028/

https://pubmed.ncbi.nlm.nih.gov/10893623/

https://journals.sagepub.com/doi/pdf/10.1177/088307380730192...

Bone mineral loss and bone health markers:

https://pubmed.ncbi.nlm.nih.gov/19064531/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6985427/

Benefits not sustained longterm. No better than high carb:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4674467/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4090010/

https://pubmed.ncbi.nlm.nih.gov/26413954/

“long-term consumption of an LC diet may increase the risk of development of gastrointestinal disorders.”

https://pubmed.ncbi.nlm.nih.gov/19224658/

Ketogenic diets inhibit mitochondrial biogenesis and induce cardiac fibrosis (in rats)

https://www.nature.com/articles/s41392-020-00411-4

Long-Term Ketogenic Diet Induces Metabolic Acidosis, Anemia, and Oxidative Stress (in rats)

https://www.hindawi.com/journals/jnme/2020/3642035/

I felt noticeably sharper on keto, which at the time I felt like was primarily a lack of sleepiness and an increased ability to focus for necessary durations. Thats how it felt, would love to see non subjective data on this.

Still N=1 but at least it’s not just ‘feeling’ clearer:

I can complete cryptic crosswords by particular setters when eating a keto diet. I couldn’t do this before.

Did I just get better at them? I’ve had two switches back to non-keto for a few weeks each and during both I could hardly start the crosswords.

I also ‘know’ I am much more able to focus and prioritise better in my work, but there is no quantitive measure I can use there.

This is probably from the increase in cortisol that accompanies VLC. I get the same feeling with alternate day fasting.

Same here. The brain likes to run on ketones.

I‘ve heard claims that it also slows neurological aging, no idea how valid that is.

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