Fat: A Brief Overview
I finally decided that I am going to do a full 3 part series on macronutrients. I am a sports performance coach and the majority of my speciality is in the weight room, but I also spend countless hours studying and reading on nutrition. Nutrition plays such a large role in not just normal people's lives, but athletes also need to understand how to utilize nutrition to enhance their own performance. A couple months back I wrote a part 1 in a blog post on carbohydrates -- check it out here if you haven’t already Carbohydrates for Sports Performance.
Let's get to it. Fats are considered a type of lipid (general group of compounds) and most of the time the terms are used interchangeably (fats or lipids). There are 3 main different types of lipids found in food or the body: triglycerides, phospholipids and sterols. I will very very very briefly go over phospholipids and sterols followed by a more in depth explanation of triglycerides.
Many people have never even heard of phospholipids partly because they are not needed in the everyday diet. This is because the body makes phospholipids naturally. Phospholipids play many roles in the body, as they are very useful in transporting fat within water in the body. Foods such as peanuts and egg yolk contain phospholipids.
Out of the 3 lipids, sterols are different from phospholipids and triglycerides in function and structure (Fink & Mikesky, 2018). The most common type of sterol is cholesterol, which is only found in animals and humans. Cholesterol is also not needed within a diet as the body produces it naturally. There are two main different types of cholesterol: low-density lipoprotein (LDL) or the “bad guy” and high-density lipoprotein (HDL) or the “good guy”. Another type of sterol are plant sterols and stanols which are certain substances that are found in vegetables, fruits and nuts. Both these have the ability to lower LDL cholesterol if ingested in the recommended amounts.
Quick run down on cholesterol. Cholesterol is found in foods such as meats, some dairy products and egg yolk. Just because you eat foods that contain dietary cholesterol does not mean it will transition to cholesterol in the body and in fact, it doesn’t work like that at all. Foods high in saturated fat will raise a person's cholesterol level. When you go to check your cholesterol levels to determine your risk of heart disease there are usually 4 different numbers: high-density lipoprotein (HDL), very-low-density lipoprotein (VLDL), lipoprotein and low-density lipoprotein (LDL). Without spending a bunch of time on each component of cholesterol I will sum it up with that you want low numbers for each lipoprotein. Wait, I thought HDL was the good cholesterol? Just because it is labeled the “good guy” doesn't necessarily mean you want a lot of it. HDL is the “good cholesterol”, but its job is to carry cholesterol in the bloodstream to the liver. I was given this analogy in my graduate studies, HDLs are like garbage trucks and their job is to get rid of the garbage (excess fat and cholesterol), but if you don't have a lot of garbage in the first place you won’t need a whole lot of garbage trucks. Basically the more HDL you have the more “garage” cholesterol you will also have. Want to lower your cholesterol? Eat well and exercise daily.
Phospholipids and sterols are not as abundant in the body compared to triglycerides, which is why I don’t think it is as important to spend too much time on the specific details of them.
Triacylglycerols or popularly known as triglycerides are the most common type of lipids found in the body and in food. They estimate that about 98% of dietary fats eaten are triglycerides (Fink & Mikesky, 2018). Majority of triglycerides are stored throughout the body as adipose tissue (fat), where some is also stored in the liver and skeletal muscle. As stated, most fats are triglycerides so they are also used interchangeably. What exactly are triglycerides? Basically just good ole fat. Before we go any further lets first go over fatty acids real quick. Fatty acids are chains of carbon and hydrogen atoms that can be either long, medium or short. Long-chain fatty acids contain 12 or more carbons and are usually solid at room temperature, where medium and short chain fatty acids are more liquid at room temperature (Fink & Mikesky, 2018). Digging even deeper there are 2 types of fatty acids, saturated and unsaturated, which include monounsaturated, polyunsaturated and trans fatty acids. Saturated fats have no double bonds to other carbons meaning that the carbons are “saturated” with hydrogens. These fats are solid at room temperature and include cheeses, butter, milk, certain oils -- to name a few. Unsaturated fats will have at least one double bond between carbons, which means they can only accept one hydrogen and won’t be “saturated”. Depending on the configuration of the carbon bonds will determine what type of unsaturated fat it is. In simpler terms, trans fat especially if the hydrogenation process (fried foods) is used would be considered the “bad” fat and monounsaturated would be the healthier fat.
Alright, so back to triglycerides. Triglycerides are made up of a glycerol (3 carbon molecule) or also known as a sugar alcohol and 3 fatty acids, hence the name triacylglycerol. Dietary fat has been frowned upon for decades, but fat still plays a large role in the body. According to a text, let’s go over the roles of fat in the body and why it is important (Fink & Mikesky, 2018).
Triglycerides are the main source of energy during rest or light to moderate intensity exercise.
It serves as a great energy storage source. Fat can be stored two main ways -- in the muscle as intramuscular triglycerides or in adipose tissue (viscerally or beneath the skin). Most fat is stored as adipose tissue subcutaneously (what you can pinch). To give you an idea of how much calories can be stored as fat, a healthy 154 pound male could have as much as 100,00 calories stored as fat.
Protects vital organs from any damage.
Serves as carriers in the bloodstream. Fat is the only macronutrient that can carry fat-soluble vitamins (A, D, E and K).
Enhances the taste of food. Hard to turn down a stick of butter on a medium cooked steak.
Enhances satiety levels. Fat carries 9 kcal/gram, which is more than twice the amount that of carbohydrates and protein (4kcal/gram) hence the feeling of fullness after an individual eats fatty foods.
It is clear that fat is important and plays many roles in the body, but too much of anything can be a bad thing. If fat is overconsumed it will be stored as adipose tissue, but at the same time if carbohydrates or proteins are also overconsumed they will be converted to fats and stored as fat tissue. It all comes down to “calories in and calories out”.
With excess body fat there comes decreased performance and multiple health concerns. It is difficult to produce energy from body fat because of how less active the tissue is compared to carbohydrates (Fink & Mikesky, 2018). Excess fat also directly correlates to cardiovascular disease, contributing to atherosclerosis and raising LDL levels. Also, the more fat you have (obese stages) the more leptin (hormone that decreases your appetite) you will have, which increases your chance to become leptin resistant. Leptin resistance actually stems from excess insulin. Insulin will block leptin at the brain not allowing you to feel full or content and so what do you do? You eat -- driving you to obesity. This is why the best single thing a diabetic can do is get off insulin. Insulin is the driving factor of obesity and the american diet has not helped one bit. Obesity is a true epidemic. To put this in perspective, a kid who is born in the 2000’s has a 1 in 3 chance of having Type II diabetes mellitus and if they are African or Hispanic they have a 1 in 2 chance. If that isn’t an epidemic I am not sure what is.
Sorry for the tangent. I find myself really passionate about the obesity epidemic in America. When obesity started to take a steep increase in America experts thought it was because people were eating too much fat, so in-return they recommended to individuals to limit the intake of fat. Experts soon found out that fat wasn't the issue, but an overconsumption of carbohydrates was.
We know that fat is the main source of energy for light to moderate intensity exercise. So the question is, in order to burn fat does an individual need to only perform low-intensity exercise (also known on the treadmill as the “fat-burning zone)? Nope, this is false. It’s this whole idea of do you have to burn fat to lose fat? During exercise you don’t have to burn fat to lose body fat. The most important factor when it comes to losing body fat through exercise is the total amount of energy burned and not worrying how much is from fat. Yes, if you perform light intensity exercise a greater percentage of calories will be from fat, but your overall calories burned will be lower. Remember “calories in and calories out” is the magic saying. This is why I think the famous “fat-burning zone” is stupid. When trying to burn a whole of calories it comes down to two factors: duration and intensity.
How much fat should an athlete be eating? Fat is the only macronutrient that isn’t technically calculated by body weight (g/kg). The Acceptable Macronutrient Distribution Range (AMDR) for fat is about 20-35 percent of total calories. This usually looks like about 1 g/kg of body weight. Athletes tend to be closer to 35 percent. The higher consumption of carbohydrates and proteins the lower the fat intake will be. Within the total fat consumption, trans fat and saturated fat should be the lowest, while the majority of fat consumed should be monounsaturated and polyunsaturated. It is important that an athlete doesn’t eat too little or too much fat as it can affect the outcome of performance.
Fat plays many roles in the body, but too much of anything can turn into a bad thing. Consuming 20-35 percent of total calories of fat and focusing on the “good” fats can lead you on the way to a healthy life and give you a competitive edge in your sport. This is just the tip of the iceberg when it comes to fat.
