no you don't. You have to have glucose for your brain to run. Understand the difference.

u dont have to input it as body makes enough

I agree with almost everything you say. However:

> Beyond how ridiculously reductive this becomes, it's impractical. You have to have carbs for your brain to run.

No. People live on no-carb diets just fine and enter ketosis. (And in any case, the comment you replied to only talked about sugar, not carbs in general.)

Not just any no/low carb diet:

'A low-carbohydrate diet based on animal sources was associated with higher all-cause mortality in both men and women, whereas a vegetable-based low-carbohydrate diet was associated with lower all-cause and cardiovascular disease mortality rates.'

https://pmc.ncbi.nlm.nih.gov/articles/PMC2989112/

It is of course rather difficult if not impossible, to have a vegetable diet completely devoid of carbohydrates.

The number of people in this study is surprisingly large!

Alas, it doesn't have much bearing on the part of the comment I wanted to focus on 'You have to have carbs for your brain to run.' Because the diets in question here still have some carbs. (And the changes in mortality rates are fairly modest, too.)

What I wanted to say is that even if you eat no carbs at all, you brain will still get its energy. You won't just keel over after a while, like if you didn't eat anything at all henceforth.

Of course, there might be second order health effects, like the study you linked suggest.

I agree with peers. Doesn’t Keto (for part of the year) worked for millennia for our ancestors?

Most of our ancestors lived a fraction of the lifespans we do.

So any argument based on “it worked for our ancestors” is flawed.

“It worked for our ancestors” could be the beginning of an idea for research, but certainly does not take you much further than that.

I agree with all you said but I also guess our ancestors mostly die from infection, hypothermia, viruses… certainly not from brain stop working because carbs amnesia.

"You have to have carbs for your brain to run" doesn’t make sense. You have to have sugar in your brain to run, but that sugar surely can comes from fat as well.

Some of our ancestors might have done keto some times, but I'm not sure most of them did most of the time? Humans are decidedly omnivorous, and most of them would eat whatever they could get their hands on, including plants and mushrooms (and sometimes honey!) etc.

iirc the inuit had a diet mostly consisting of meat and fish, but - according to wikipedia - not even they were usually in ketosis.

They also had carbohydrates in their diet. Meat naturally contains carbs. Pretending that the human body is misunderstood and that it worked very differently is a common pitfall of these discussions. Largely it was the same, with the amounts differing.

Meat contains only insignificant amounts of carbs. The human body can convert protein to carbs (glucose specifically) but the rate at which it can do it is limited, and my guess is that if it can't burn glucose, a metabolically-healthy body will burn fat (rather than glucose made from protein) until the diet has been quite deficient in calories for at least 3 days.

No. You dont.

There are other metabolic pathways to produce glucose (or produce ketones). The other pathways ‘push’ the body more since they have to do some conversion. This ‘extra effort’ is considered to be more healthy.

Yes there are. You still need carbs and you get them (ie celery has carbs), regardless. Repetition wont convince someone arguing in bad faith, so I will bow to your religious beliefs.

Yes you need to have carbs, however the quality of the carbohydrate is the most important factor.

If you have any sense for your health you will not have regular intake of sugar, white bread, potatoes crisps, rice cakes, any thing with a high GI.

Some carbohydrates reduce your risk of diabetes, and if you're smart you follow the evidence and you eat these-

https://youtu.be/DNQrNWsoPEE?si=GORRP5IblhNkKCdF

>You have to have carbs for your brain to run.

The brain can run well on ketone bodies (which the liver makes from fatty acids). In fact, causing the brain to run on ketone bodies is used by doctors to treat illness (and not just epilepsy).

The human brain can run on up to 70% ketones overall (this is not only safe, but it appears to have additional therapeutic benefits) and your body can synthesize glucose in your liver and kidneys from fats and proteins though gluconeogenesis to supply the remaining parts of your brain that can't metabolize betahydroxybutyrate, acetoacetate and acetone.