I also have found that I don't need as many calories if every single one of them is packed with nutrition. 800 calories/day of WW food would be torture but primal food is more nutrient dense.
When I was really losing on Primal I was eating about 1000-1200/day and everybody was wringing their hands about "starvation mode" etc. The thing is, once you are in ketosis, you are not really only getting that low intake. Your body is supplementing it with a tasty fat snack off your thighs and rear.