Beef Liver good?

I have been doing well on my current diet and at this point Im down about 21 pounds. My workouts are geared toward MMA so I on most days after practice we go 3-4 live 5 minute rounds which exhausts me to my limit some days.
I recently started eating 1-2 4oz servings of beef liver per day for maybe 4 days and then take a couple days off.
Its weird, because I never cared for liver but recently started craving it. I restrict it to just a few days because im not sure if its good to eat too much of it.
Just courious if anyone has any advise as to how often and how much is healthy to be eating.