Ok, it’s time to put on our grownup organic chemistry pants. Yes, I know they’re snug and just a little itchy, but to fully understand saturated and unsaturated fats you gotta get down on the molecular level. Are you ready to get down? That’s the spirit! I like your energy.
What is fat besides something you pay a monthly gym membership fee to get rid of?
In order to keep that crazy dance called living going the body needs protein, vitamins, carbohydrates, and lipids. Huh, Lipids…? Let’s chat about molecules for a second. Lipids are a broad category of molecules to include cholesterols, phospholipids, and triglycerides. Your cholesterols can be supplied by your diet and tend to make up things like cell walls and some hormones. Don’t worry, I wrote another article about them. Phospholipids, like all lipids, have the curious property of being hydrophobic, a portion of the molecule refuses to mingle with water (haters are gonna hate) which creates a situation where long chains of phospholipids will form structures that contort and close in on each other to keep the water out. This makes the molecule ideal for forming things like cell membranes and vessicles.
Now what we call fats are another name for that subgroup of lipids called triglycerides. They look
something like this…
Do you see this madness up there? That’s a triglyceride (fat) molecule….well the atomic formula for one. It has a glycerol unit that connects 3 fatty acids like the handle to a 3 pronged Afro pick. Oh don’t turn your nose up to this diagram. This is where we need to play. You see all those happy little hydrogens? There’s something you need to know about the element carbon. It loves attention, how else do you explain an atom that can bond up to 4 atoms at once. It’s more high maintenance than a bitter, Hollywood Hills divorcée.
Carbon has a deep and real connection with Hydrogen and will give all of her time (bonds) to it but she will also bond with another Carbon if there’s a space left. She’s…um…adventurous. Anyway, when carbon and hydrogen are exclusive they like to form these really long chains that are structurally uniform. They look something like this…
When carbon has a space free (unsaturated) and or double bonds to another carbon it forms a kink in the chain and that structure changes the way that fat will now behave. Saturated fats contain chains of carbon bound exclusively to every available hydrogen. So they are “saturated” with hydrogens. Unsaturated fatty acid chains are a little friskier, molecularly speaking, and have kinks in the chain as a result of one or more missing hydrogen pairs.
These structural changes affect the way the molecule behaves and it’s the behavior of molecules that we really care about. So how do they behave?
Well since saturated fats are so DANG uniform, the triglyceride molecules they form can stack on top of each other really well like Lincoln logs…oh wait, were you born after the 80’s? I mean they stack like Jinga blocks. So saturated fats tend to form solids at room temperature like butter, A.K.A the Golden God, or like the bacon fat you watched cool in the frying pan that one time and for a second you thought to yourself “is that what it’s doing in my arteries?” Yes, that’s exactly what it’s doing. You knew what you were doing, but you didn’t stop did you…DID YOU?!
Because unsaturated fats are so kinky (tee hee) they don’t stack as well and thus tend to remain fluid at room temperature. These are the olive, cannola, vegetable oils that are far better for your ticker (heart healthy). When they describe these fats as mono or polyunsaturated they are referring to whether or not there is one (mono) or more (poly) hydrogens missing from the fatty acids.
Trans fats (when fats attack)
Yeah, unsaturated fats are great and all but since they’re a little light on the hydrogens, stray elements like sulfur like to wander in every now and then and make those oils go rancid when left unattended. So they tend not to have a great shelf life and they don’t exactly spread or bake like butter. Trans fats happened because manufacturers partially hydrogenated (added hydrogens) to unsaturated fats. As a result, you can eat honey buns that have been in the vending machine since the Clinton Administration but they’re about as healthy for your heart as crude oil.
I hope that clears a few things up. Stay curious, stay classy, and never stop learning my friends 🙂