Many thanks for the article Psyche. I managed to read the whole thing, I think the tablespoon of lard I ate helped. This line caught my attention:
KBs begin to be utilized as an energy source by the CNS when they reach a concentration of about 4 mmol/l
Seeing that my levels have only reached 3.6 mmol/l at maximum tells me I'm doing something wrong. I'm thinking that I'm slacking off on the fat again. I've been finding it difficult to concentrate on reading, and having somewhat excessive emotionality and panic attacks, although I'm not sure if the diet is the main cause. Anyway, I notice a difference and I want my ketogenic brain back! I blame myself for not actively measuring my fat intake. I'm upping my tablespoons of lard per day to 10-12, from something like 4-5 previously. Based on a 1800 calorie intake I should be at 180g fat, with protein at 48g, carbs 0.
I think I may be missing the butter that I used to eat because it tastes a lot better. It could also be that dastardly old anti-fat programming as Laura mentioned way back in the thread. The taste for lard definitely develops with continuous intake, however. If I'm not wrong it's got something to do with the upregulation of the CD36 receptor.