Nutritional ketosis (eg for fat loss) only requires getting the carb intake low enough for ketones to be detected in the urine,
No I wouldn't say that. I would scythe ketones excreted through ruin are waste or unused ketones, and that over time the amount of ketones excreted will decrease, so just because the urine strip doesn't turn purple doesn't mean you're not in ketosis, the only accurate way of measuring ketone levels is via blood. The 50g threshold for ketosis may vary from person to person but on average yes if you dip below this level you should be able to enter ketosis easily.
People opt for low protein because they believe that the protein causes an insulin spike which exacerbates their insulin resistance, the spike is only minimal, but whats more important a tiny insulin increase or destroying your lean body mass!!
Therapeutic ketosis requires a high level of ketones as fuel for the brain,
The body and all of the cells in the entire body prefer burning ketones as a primary fuel source not just the brain, but the brain loves it!! remember the brain is about 90% fat anyways, so whether it is for nutritional or therapeutic ketosis the ketones are used as the primary fuel. the main reason for maintaining high levels of ketones, and to ensure low levels of glucose basically to starve of the cancer cells as they need sugar constantly to divide and replicate themselves. They also help to enhance repairing of the neurons.
people can eat 75% calories from fat without feeling sick?
Yes it seems people can quite happily put away vast amounts of fat without feeling sick, although I would never recommend anyone to have this much fat as a percentage of total calories unless they were doing therapeutic ketosis.
Does it make a difference whether you're eating good fats or bad fats?
what is a good fat, what is a bad fat?
I think when you consider that most meats have a good mix of all three trans, saturated and unsaturated fats they aren't really the issue, what I think is more important is the ration of Omega3 (healthy) and Omega 6 (inflammatory) fats. I certainly do not recommend any highly processed oils such as canola, or vegetable oils, the seed oils I haven't quite made my mind up on them yet, but I tend to stay away from them. As far as Cholestrol and triglycerides are concerned I would be more concerned about the triglycerides made in the liver through glucose storage than I would be from eating it from healthy fats such as butter, olive oil, tallow or lard.
last year the CANTOS study clearly identified that the vast majority of Cardiovascular disease is attributed to the inflammatory processes occurring in the body and that by treating the inflammation they can actually reduce the risk of heart disease without even touching the levels of cholesterol.1