There are 2 methods I use for determining calorie intake
1) BMR + Approx. calories burned through cardio + Approx calories burned through training
2) Bodyweight X 14-16... 14 for low metabolism, 15 for high metabolism, 16 for high metabolism/or being on T3.
Both are just approximations, eventually you find out through trial and error where your true caloric expenditure lies.
I must say I'm not a huge fan of the high fat/protein Keto diet. I think it works decently at higher body fat %ages. It's easy to follow and calculate. The high fats keep you full and repel hunger. But my main gripes with the high fat/protein CKD is sustainability. Even with re-feeds sustaining training sessions and cardio sessions becomes exponentially harder, the longer you do it.
When you think about what has to happen to free stored fats and transport them to the mitochondria, it seems to be not very efficient. Glycogen depletion is key to this cconcept. And the problem is, in the full absence of carb sources training hard enough to fully deplete glycogen becomes very hard, if not impossible.
TKD is a step ahead in that department because you have pre-workout carbs to sustain the workout volume you need to fully deplete glycogen. Remember when you are glycogen depleted enough, carbs taken in will go towards glycogen replenishment and not to energy use or fat storage.
The best thing is an oxymoron... basically variations of the anti-keto to keto diet. I say that jokingly, but it is basically true. With high training intensity depleting glycogen further and further you can eat enough carbs to support training/cardio and you still maintain the fact that you are using stored fat.
I hope that makes sense, I tried to figure out how to explain it best.
My number one new dieting concept is to base diet on training.
Another new thing that I have been tooling around with is severely restricting calories ala the ultimate diet 2.0... I've been running 3.5 days at 50% of maintenance as described in #2 above. I'm shredding big time, and the rebound from carbup into maintenance is unbelievable.