God tells us to not eat the fat from an animal which may be offered as a sacrifice, such as an ox, a sheep or a goat (Le 7:23-24); violating this rule imposes the death penalty. (25) Since all God’s Law is spiritual and good (1Ti 1:8) we should be obeying this principle.
As a bit of context, while God says the fat belongs to Himself (Le 3:16-17), He also describes the location of the fat as that which covers the animal’s flesh and internal organs. (14-15) God doesn’t require us to shred sacrifices to remove every trace of fat.
As with the blood, which we’re also forbidden to eat (De 15:23), it isn’t generally reasonable or practical to try to remove absolutely all the fat from any cut of meat. No matter how well we slaughter an animal and drain out the blood, some blood cells will always remain within the flesh. The idea seems to be that we are to avoid eating animal fat as a focus, we trim it out where it’s reasonably practical to do so.
When God blesses His people with the fat of lambs (De 32:13-14), it’s clear that all fat isn’t forbidden; baby lambs simply don’t have much fat; what little is present is evidently intended for us to enjoy.
So, we should trim the fat off the outside of a cut of meat and then enjoy the flavor-enriching marbling within as we like; not in rigid, legalistic fastidiousness, becoming judgmental, fretful or worried about getting out every trace of fat, yet not casually eating easily isolatable chunks of it either.
As in applying most any aspect of Torah, especially in non-Torah observant contexts, reason, love and moderation ought to rule the day. (Php 4:5)
We might ask why God forbids eating fat. Is it bad for us in a nutritional sense? Do animals tend to store more toxins in fat than in other parts of the body?
Since God hasn’t told us clearly, perhaps we don’t need to know. Perhaps this is a foolish question; having the answer may not help us in our walk with God. (Ti 3:9) Evidently, we don’t need to know why God tells us what He does, we simply need to focus on clearly hearing and fully understanding what He says so we can obey Him in wisdom, love and joy. (Ps 119:3-4)