Fat represents the best. Theologically, a worshipper presented the fat of the sacrificial animal because it was the best of the flock. Rather than selling the animal for a good price at the market, the true worshipper saved the best for the Lord. To eat the fat of the animal would be to rob the Lord of what belonged to him.
23 Parle aux enfants d'Israël, et dis:Vous ne mangerez point de graisse de bœuf, d'agneau ni de chèvre.