The Lord did not want Israel to eat the fat of any animal,
And the Lord spoke to Moses, saying,
“Speak to the children of Israel, saying: ‘You shall not eat any fat, of ox or sheep or goat. And the fat of an animal that dies naturally, and the fat of what is torn by wild beasts, may be used in any other way; but you shall by no means eat it. For whoever eats the fat of the animal of which men offer an offering made by fire to the Lord, the person who eats it shall be cut off from his people. Moreover you shall not eat any blood in any of your dwellings, whether of bird or beast. Whoever eats any blood, that person shall be cut off from his people’” (Leviticus 7:22–27).
Yet, later in Nehemiah 8, you will read this,
Then he said to them,
“Go your way, eat the fat, drink the sweet, and send portions to those for whom nothing is prepared; for this day is holy to our Lord. Do not sorrow, for the joy of the Lord is your strength” (Nehemiah 8:10).
Perhaps in their zeal to keep Leviticus 7, they would spend endless amounts of time trying to remove every speck of fat found in meat, when in reality it would be impossible to dissect every tiny piece of fat.
The Lord did not want them to eat the large pieces of fat attached to meat, but then to go ahead and eat the rest of the meat, although there would be traces of fat in it.
Thus, in Nehemiah 8, Ezra and his friends urged their fellow Jews to enjoy the food.