This is a logical fallacy. Just because you say it's a fact doesn't make it so. Please provide evidence showing that "the vast majority of hunter gatherers" were low carb.
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The further and further you go back in the paleolithic timeline, the less meat and fat you find and the more fruit and starch you find. A lot of this has to do with the fact that we didn't develop the technology to survive in cold weather environments where fatty game is common until fairly recently. The traditional societies today are almost exclusively higher carb, and the societies with higher fat intakes in existence today has their fat coming mostly from coconuts, nuts and seeds, not fatty animals. I think you couldn't be more wrong. Even Inuits, the most extreme society the low carb zealots argue for, ate ~15% of their dietary calories from carbs, which is significantly more than you get on keto.
Again, you have no evidence that show the majority of hunter gatherers were low carb. The evidence I presented shows the exact opposite. "Because I said so" is not an argument. There is also no evidence that eating whole food carbohydrate while sedentary is damaging.
The best way is to stop thinking in terms of fat and carbs and just think in terms of real food. It doesn't matter if it's meat, fruit, roots, tubers, nuts, potatoes or vegetables. If it's real food and it makes you feel good, eat it.
Avoiding grains, legumes and refined oils has been shown to be effective at reversing metabolic syndrome. Show me a study where macros were held the same as on the SAD, but replaced all the grains and legumes with sweet potatoes, plantains and fruit. Low carb diets naturally eliminate grains and legumes due to the starch content. It's not the carb removal showing the improvement, it's the removal of toxic lectins.