 Hey everybody, Dr. O here. Let's talk about fats or triglycerides. So there are other types of lipids. You've got sterols and phospholipids, but our lipid we care the most about is going to be the triglyceride because this is the kind of fat we eat and it's also the kind of fat that's on our bodies. So why is it called the triglyceride? As you see here, it has a glycerol backbone and three fatty acid tails, so triglyceride. The glycerol backbone is actually useful as a fuel. We primarily talk about the fatty acid tails and I'll teach you later when we get to metabolism about how these long fatty acid tails are digested and broken down for fuel. But the glycerol backbone can actually be converted into glucose in a process called gluconeogenesis. If you run out of glucose in your body, it has to start to make some and it uses this gluconeogenesis. Most that comes from proteins. Your body can turn proteins into glucose, but you also can convert the glycerol backbone into glucose too. So that's kind of what makes glycerol important, I guess. Those fatty acid tails are where we're going to spend most of our time. So notice that they are hydrocarbon tails, they're full of carbon and hydrogen. There is some oxygen there, but that's going to be in a functional group on the end. You don't see a lot of oxygen, which is the reason that fats have nine calories per gram, whereas carbohydrates only have four calories per gram. Carbs have a lot more oxygen, which is big, much bigger than carbon and hydrogen, so you can't cram as many calories into a gram of carbs as you can fat. So fat's going to be the most energy-dense thing we consume, nine calories per gram. Very important fuel at rest. So fat, there's a lot of energy in fat, but it burns pretty slowly. I always think of it kind of like a log on a fire, right? You're going to get fuel from that for hours and hours, but if you need quick fuel, like you're going to need dried kindling, newspaper, that's like carbs. Carbs are going to be quick energy. So carbs are your primary fuel source when you're physically active, but fats, like these triglycerides, are going to be your primary fuel source at rest. All right, let's go ahead and dive in. So the first thing I think about when I think about these fatty acid tails is their length. So there are different types of fats based on length. We have short chain fatty acids, medium chain fatty acids, and then we have the long chain fatty acids. And I'll do a separate video where we talk about some of the very long chain fatty acids. Short chain fats, I primarily think of dairy products, butyric acid or butyrate is the best example here. So there is some of this in things like butter and cheese, that type of thing. The organisms inside your large intestine actually make some of this. This is butyrates the primary fuel source for the cells of your large intestine. So short chain fats are important, but not a big part of the diet. Medium chain fatty acids, I like talking about these. They're also called medium chain triglycerides, and maybe you've heard of MCT oil or medium chain triglyceride oil. Another place where you're going to find a lot of medium chain triglycerides is coconut. So coconut, coconut oil, MCT oil, they've been touted as being healthy and great for athletes, and there's a good reason for that. They're a good energy source. Your body can burn these medium chain fatty acids easier than the long chain fatty acids. It actually can convert them into ketones. So when you consume MCT oils, your ketone levels will go up, and ketones are a great alternate fuel source. The other cool thing about the medium chain fatty acids, they don't need bile. They're absorbed into your bloodstream. They don't need bile to be carried into your body, so they're going to be absorbed a lot more quickly, and they're going to be used as energy. So I think medium chain fats are a great energy source. I keep my bottle here. I'm not sponsored at all, but I consume MCT oils, and I think they're very good for your brain. So those are the medium chain fats. But when we're talking about fats, unless I specifically say short or medium chain, they are the long chain fatty acids that we talk about primarily. So let's go ahead and look at that. So chain length is the first thing I think of when it comes to fatty acids. Next is going to be their saturation, so I'm sure you've heard terms like saturated fat. So this is going to be what a fatty acid tail looks like. We just talked about length. So now we're going to talk about saturation. Before we move on, notice here on the left we have the omega end of a fatty acid tail. That term is going to be important in a little while, because we're going to talk about omega 3, omega 6, and omega 9 fats. That omega number tells you where the last double bond is. So we'll come back to that. That's why the omega end matters. Let's start with saturated fats. So here at the top you see a saturated fat like steric acid. So saturated fats are called that because they're saturated with hydrogen. Every carbon has as many hydrogens around it as it can, which is why there are zero double bonds. So the key thing to note with saturated fats, no double bonds. You see a double bond there on the left, but that's a functional group called the carboxyl group. In the tail itself there are no double bonds. So because they don't have double bonds, they're straight. Notice how the double bond in the oleic acid underneath there causes that kink in the tail. So since all of the tails on saturated fats are flat and straight, they're going to stack together, which is why saturated fats are solid at room temperature. So those are the two key things to remember right now. Saturated fats have no double bonds, zero double bonds, and they're solid at room temperature. Butter and lard would be great examples of foods that have a lot of saturated fats, but don't be fooled by that. Lard actually has as much as many mono and saturated fats as olive oil does. It's kind of complicated. So here we see if you have one double bond, this will be a mono and saturated fat. Let's go back to that other picture. So oleic acid, which is very high in olive oil, is gonna be a mono and saturated fat. So these are very good for you. A lot of health benefits to mono and saturated fats, but that kink makes it so these tails can't stack on top of each other. This is why mono and saturated fats are liquid at room temperature. So olive oil is a liquid at room temperature. Lard would be a solid. So that's gonna be your mono and saturated fats. We'll cover all the health benefits stuff later. Then here, if you have a fatty acid that has more than one double bond in these tails, they're going to be poly and saturated fats. These will also be liquid at room temperature because they have these kinks in the tails. A lot of your plant oils are going to be your poly, have a lot of poly and saturated fats in them. So looking at different types of fats here. So we talked about saturated fats, usually being animal fats and then some of the tropical oils, unsaturated fats. We have the mono and saturated fats. The first thing most people think about would be olive oil. I like to like avocados and avocado oil are a great source of mono and saturated fats, nuts like almonds as well. Then we have the poly and saturated fats. They're gonna be the omega-3s and the omega-6s. We're gonna do a separate video on those two because they're so important because they play a big role in inflammation and these kind of things. Now I'm gonna go back if I would say one thing just about how the biochemistry here has links to health would be these double bonds. Anywhere you see a double bond, these are fragile parts of fatty acids where they're more likely to be oxidized. So the more double bonds a fat has, the more likely it is to be oxidized by free radicals and potentially be rancid. So from a health standpoint, what I recommend is if you have a fat that's high in saturated fats, you can probably keep it two, three years. They're very stable. If you have a mono and saturated fats, I generally recommend not using them if they're more than six months old because these double bonds are fragile and over time, heat, oxygen, light, these things are gonna create these free radicals that will damage the fats and make them become rancid. So I go two, three years probably good for something that's really high in saturated fats, six months for things that are high in mono and saturated fats like olive oil, and then three months for things that are high in poly and saturated fats. And I can talk about that more when we talk about the omega three and six fats. So that's a brief introduction. I know it's kind of long, but there's a lot to talk about here. A brief introduction to triglycerides or fats. I hope this helps. Have a wonderful day. Be blessed.