I never said the brain can use LCFA for fuel, but the brain can not survive solely on ketones hence the reason for glycogenesis.
Inflammation of the arterial wall comes from excess consumption of carbohydrates. Cholesterol will "stick" to the wall because of this inflammation like glue causing blockage over time. Blood levels of cholesterol are meaningless as far as heart disease is concerned. Remember all carbs break down into glucose in this instance it doesn't matter where they come from.
you said the brain can not use fat for fuel. which is partially true because it can not use long chain fatty acids for fuel.
it CAN use ketone bodies (product of fat consumption) for fuel.
i disagree on the point that the brain cant survive solely on ketones.
thats what ketones are actually for. i wouldnt mind if you could prove me wrong with a source though
gluconeogenesis is the survival mechanism that takes place if you eat
no fats or carbs... = glucose is produced from protein in order not to die
ketosis is the suvival mechanism that takes place if you eat no carbs... which is a much more natural condition (but im not one of those paleo guys).
ketosis is much more energy efficient than gluconeogenesis too.
strongly agree on your second point, i know that and i know you can have the worst cholesterol profile ever without having any issues as long as there is no systemic inflammation present.
but id assume systemic inflammation is caused by excess SUGARS, not carbohydrates. you say inflammation comes from excess carbohydrate consumption... if you consume 100g of dextrose then there ARE plenty of excess carbohydrates in your blood, since its a simple carb and absorbed extremely quickly.
if you consume 100g carbs from oatmeal though then it takes your body several hours to break down the complex carbs into glucose and this results in a MUCH LOWER glucose influx at once.
sooo the release of 100g glucose OVER lets say 3 hours FROM OATMEAL is of course MUCH different than the immediate release of 100g straight glucose (from soda or whatever)
you say EXCESSIVE carbohydrates cause inflammation.
100g straight glucose are excessive.
100g glucose spread out over 3 hours (from digestion of oatmeal) might NOT be excessive and therefore NOT cause inflammation.
thats why i say complex carbs have a different effect.
edit: okay ive read up, its been proven that the brain can use fat (ketones) for approx. 75% of its energy requirements. it needs about 20-30g glucose which can be synthesized from various sources (most likely amino acids, as you said).
so youre correct on the point that the brain needs SOME (albeit only a miniscule amount) of glucose to function. the main portion of the energy requirements can be covered from dietary fat though.
http://www.ncbi.nlm.nih.gov/books/NBK22591/