Ch 2.5.3 Lipids - The Body’s Scapegoat

Lipids - The Body’s Scapegoat

Much like the carbohydrates we just talked about, most lipids are also composed of carbon, hydrogen, and oxygen but unlike carbs, lipids have a shit ton more hydrogen than they do oxygen. While they’re technically not true polymers, we talk about them at the same time as all the others because lipids are big, making them macromolecules, and they are important, making them worth your fucking time. Without lipids, we wouldn’t have any steroids, which include hormones, no fats, no waxes, and no cell membranes. We’ll come back to discuss the types of lipids found in cell membranes when we go through the parts of the cell so for now, we can discuss fats.

Fat has this negative image because a lot of people have too much of it and want to get rid of it but the healthiest of people still need some fat. When you look at professional bodybuilders, they’re still rocking a certain amount of body fat. Granted, it’s in the single digits percentage-wise but if they had zero percent body fat, they would be dead. (Coincidentally, a lot of them use extra lipids in the form of steroids but that’s not for me to judge.) Now when you look at a molecule of fat, you’ll see two distinct sections, the glycerol group and the fatty acid tails. Glycerol is an alcohol meaning it has at least one (it actually has three) hydroxyl (-OH) groups which serve as attachment points for the fatty acid tails by means of a dehydration reaction. The fatty acids are called this because at one end they have a carboxyl (-COOH) group. When the hydroxyl and carboxyl groups come together, a molecule of water is lost and BOOM! They’re joined together. Its entirely possible that all three fatty acids in a given fat molecule are exactly the same or they can be different, it doesn’t really matter.

What does matter is how those tails are constructed. The terms unsaturated fat, saturated fat, and trans fat come into play here and refer to the nature of the fatty acid. In an unsaturated fat (these are the “good” fats) there is at least one carbon-to-carbon double bond in at least one of the tails. In this sense, they are unsaturated with hydrogen. Alternatively, saturated fats are chocked full of hydrogens and everything is a single bond, single bonds as far as the eye can see. Comparing the the two, because of the orientation of the double bond in unsaturated fats (what’s known as a cis bond because the big parts are on the same side of the double bond), these fats can’t pack together as tightly as saturated fats can and as a result, unsaturated fats tend to be liquid at room temperature (all your oils) while saturated fats tend to be solid (butter, lard, etc). A trans fat is an unsaturated fat they turned into a saturated fat by a chemical process. They can also be partially-hydrogenated and in this case, the normally cis-oriented bonds become trans oriented, meaning the big parts are on opposites sides of the bond, and giving the trans fat its name. While this is no means a healthy living book, the majority of people say unsaturated fat good, saturated fat ok, trans fat bad.