I'm pretty sure the Egyptians had the ability (and slave labor) to make white flour with manual sifting, and if the temples were getting the "best" bread and cakes in offerings they were probably made with the most refined grains possible. More refined foods (grains, sugars) have held prestige for a long time in various civilizations because they require so much labor to produce, so temples being offered the most prestigious foods as offerings probably got a lot of it. But of course, they focus only on the saturated fat.