If you are ZC I don't think your constant fat intake matters. I think you need to do it by taste because too much fat or too little fat is bad depending on your body fat %. Keep the meat constant, by taste/desire, with whatever fat comes with it. Then only add extra fat if you feel like it. This will be if your body-fat reserves are running low. If they're high, you won't desire so much fat and shouldn't eat in excess of what comes with the meat/what little extra you feel like possibly. I think the body wants to store any fat you eat first anyway before using it, so you only need to eat fat to keep your own body-reserves up. Which will be more, the more energy you use. Whilst you're digesting a meaty meal, I think the body is using some of the protein for energy too but I'm not sure, it might just be storing that energy in some carb form such as glycogen. I really don't know about that last bit.
If you eat more fat than you use over a long period, your body won't put it on past a certain point but your body does 'stupid' things to use it up. If you eat less fat than you use over a long period, you will stop losing body fat past a certain point, but your body will do 'stupid' things to spare what's remaining. When it comes to fat, if you already have a decent store in your body, it seems better to play catch up and top up your fat after it's depleted, than to try the other way around(trying to add it before you use it).
