D: You know, it seems like you can't turn on the TV anymore without seeing      commercials for foods that are low in saturated fats. I can't remember the last time I      ate real butter. I don't get it. What is it that saturates fat and makes it so evil?

Y: Well, Don, the answer is actually pretty simple. Saturated fat is saturated with      hydrogen.

D: Hydrogen? That's it? But there's hydrogen in my water and no one tells me to stay      away from that.

Y: You see, Don, fats are mostly made up of molecules called fatty acids, and saturated      fats are made up of saturated fatty acids.

D: Okay, but what are saturated fatty acids?

Y: I'm getting to that. Fatty acids consist of chains of carbon atoms, which have four      spaces for connecting to other atoms. Two spaces are connected to neighboring      carbons, and if the other two are filled with hydrogen the fat is considered saturated      --that is, saturated with hydrogen.

D: Alright, that explains why they're called "saturated" fats, but what's so wrong with      them?

Y: Well, Don, your body uses fat to absorb cholesterol from the food you eat, and      saturated fats absorb cholesterol super efficiently. But too much cholesterol in the      blood can be dangerous. It builds up on artery walls and increases your risk for heart      attacks and strokes. So a diet low in fat, and low in saturated fats, helps reduce the      amount of cholesterol your body absorbs.

D: So I can like butter, but I can't love it.

Y: Everything in moderation, Don.  

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