I've been playing with some numbers for after the Fat Fast. One of the things I am enjoying on the low calorie plan is the mental clarity. I wondered how low cal I could eat and still get all my macros. No, I am not dropping my cals to starvation, just thinking about Dr Seyfried's cancer work and his low carb, medium protein, low cal tenets. He suggests eating 30% below BMR (for me 1250 cals), which I would do if I had cancer.
If my carb goal is 20, my protein goal is 60, and I want fat at 80%, then the lowest I could eat is 1600 cals. If I add in 15 more grams of protein, that brings me to 1660 but only 76% fat. I would have to eat 1900 to get back to the 80% fat level.
Therefore, I see my calorie goals should be nearer to 1600 on non workout days and 1900 on workout days.