> I think a better heuristic, is "Just eat what your great-grandma ate". Or avoid the middle of the supermarket as much as possible.

I like that!

I had some friends over for a small dinner party a few weeks back. One of them was helping me in the kitchen butter some sour dough bread. Mid-way through she stopped agog just staring. I looked to where her eyes were staring and realized she was shocked at how much butter I was smearing on each slice of bread.

I'm active and believe in eating a lot of natural fats, but I realized that even young adults subscribe to the demonization of saturated fat. (I might also be a little too inclined to eat butter and coconut oil - so moderation - as always is important if we're to not alienate everybody).