Whats the difference between trans fat and saturated fat?

Um, wikipedia? But since I’m feeling friendly…

Generally speaking, the main difference between the two is the fact that saturated fat is fat that occurs naturally in foods such as butter, cheese, and meat. Trans fat is a man-made fat created by partially hydrogenating plant oils. A lot of fast food and processed food products have trans fat in them. They’re both not great for you, but generally speaking you should avoid trans fats at all cost and try to limit your intake for saturated fat.

For more info:

http://en.wikipedia.org/wiki/Saturated_fat
http://en.wikipedia.org/wiki/Trans_fat

When organic molecules (like fats) are called “saturated”, that means that they have hydrogen atoms attached to every place they could possibly be attached on the carbon atoms in the molecule.

If they’re “unsaturated”, that means that some of the places a hydrogen atom COULD be do NOT have hydrogen atoms. If a hydrogen atom isn’t filling that spot, the carbon atom has an opening for a new bond. In the case of fats, this means that it bonds with the carbon atom that’s immediately next to it. Since these carbons are next to each other in the same molecule, they were already bonded together once, so this second bond forms a double bond.

Double bonds have different characteristics from single bonds, and one of these differences is the shape the molecule takes. Double bonds can be either “cis” (that is, the two heaviest/most “important” groups are on the SAME side of the bond) or “trans” (the two heaviest/most “important” groups are on OPPOSITE sides of the bond).

So in summary: there’s one kind of saturated fat, but TWO kinds of unsaturated fats. Those two kinds are “cis” fats and “trans” fats, and the difference between those two things is the arrangements of the atoms bonded to it around a double bond between two carbon atoms.