Trans fats, saturated fats, polyunsaturated mono gluta-what? People toss these words around all the time, good fats and bad fats, and what you should and shouldn't be eating, but what are they really talking about? All right. So first, we have to talk about what a fat actually is. Fats all have a pretty similar chemical structure of three fatty acid chains stuck onto a glycerol molecule to make a triglyceride. These fatty acid chains are long strands of carbon atoms arranged in a zigzag pattern. Now, we have to step back just one second to carbon bonding. Carbon atoms each have the ability to make four chemical bonds. So in fatty acid chains, each carbon atom is using one bond to hold onto the carbon in front of it and one bond to hold onto the carbon behind it. In many fatty acid chains, all of the other available bonds will be filled with hydrogen atoms. In this case, the fatty acid chain is said to be saturated with hydrogens, a saturated fat. Now, it's possible that two of those carbon atoms could double bond to each other. The formation of this double bond would mean that some of the hydrogens would disappear. Thus, the fat would now be an unsaturated fat. If there's only one double bond, it's called a monounsaturated fat. And if there are more, it is called a polyunsaturated fat. The carbon chain would additionally have to bend to accommodate this double bond. This means that instead of having a nice zigzag, you now have a kink in your fatty acid chain. Now, zigzagged fatty acid chains are all the same shape, so they stack very well. This stacking creates things like solid fats, like a stick of butter. However, unsaturated, kinked fatty acid chains don't stack very well, so they create things like liquid fats, like oil. So what about those trans fats? Well, trans fats are also unsaturated fats, but their kink goes in the opposite direction. This naming is based on the difference between cis and trans bonds. Cis means on the same side, whereas trans means on the opposite side. So while there is still a kink in this bond, the trans fats actually stack pretty well and can form solids, and they're not too easily broken down by your body. So not so great. May your ingredient lists be a little less mystifying. Go forth do science.