I’ve read through this and I can vouch for low/no carb diets. I was 165 lbs and around 21-ish% body fat. I set aside 2 months of a low carb diet, and I basically just worked out and did a lot of aerobic exercises at the end of my workouts.
The key to this is a caloric defict and a lot of sweating. Drink water, pee it out, sweat buckets. At the end of each workout I lost around 6 pounds+ of water weight.
My diet consisted of a banana in the morning, a huge (and great) salad at lunch (Around 1pm) and basically just meat and veggies during dinner (8pm).
The key to the diet is a lot of exercise, and basically no carbs or sugar. (Carbs are broken down into simpler sugars, fyi)
But I still drank a bottle of gatorade after a workout, mostly so I can curb the cravings and rehydrate.
2 months of this and I dropped 20 pounds and was around 12% body fat.
After the 2 months I stopped the diet (This was around 2015, by the way.) and since then my workouts have been fluctuating going from working out minimally to every day for months, and I still retain by 12% body fat, but i’m now around 160lbs.
Also regarding the diet of our ancestors, I do want to add that there is some cause to belief that early humans were scavengers - picking off meat from freshly slain animals by other predators, and eating marrow inside the bones of said animals. Which I add, marrow has a high fat content, and is believed to have aided the growth of our brains.