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The Role of Fats in our Diets

Fats are an essential macronutrient that your body needs. Macronutrients are nutrients that we need in large amounts. Macro=large. Fats are essential for hormonal health and the absorption of fat soluble vitamins (A,D,E,K). For example, if you take a vitamin D supplement consuming it with food is going to help the absorption. Cholesterol in the skin is also a precursor of vitamin D absorption. Cholesterol also plays a role in the synthesis of steroid hormones, estrogen and testosterone, and cortisol and aldosterone. Your liver synthesizes cholesterol your body needs, therefore it is not essential to consume. Fat is also essential for the formation of cellular membranes and protection for our organs. Fats are 9 kilocalories per gram, more than double that of proteins (4 kcal/g) and carbohydrates (4 kcal/g). Because of this, fats are going to be a large source of energy. While at rest fats are going to be where we are getting the majority of our energy from. They are also easier to overeat and easily stored in the body. Over eating fats will not result in weight gain if it does not result in an overconsumption of calories. Fats are mostly stored in adipose tissue. However, they can also be stored in the muscle and there is a small amount of fatty acids in our blood. The body has the ability to store excess energy as triglycerides in an unlimited amount in the adipocytes (fat cells). Fat cells can grow to 1,000 times their original size.


Types of Fats


Types of fats include saturated, trans, polyunsaturated, and monounsaturated fats. Really the differences between these fats all comes down their molecular structure.


Saturated fats are going to be solid at room temperature s well as animal fat sources. Coconut oil is an example of a saturated fat. It is recommended that less than 10% of your diet comes from saturated fats. It’s impossible to eliminate saturated fats from your diet because a lot of healthy foods still contain saturated fats. Eliminating all saturated fats from your diet could lead to low intakes of essential fatty acids, fat soluble vitamins, proteins, and calcium. Consuming low fat versions of foods (ex: low fat dairy products) will help decrease the consumption of saturated fats.


Trans fats are fats that you are going to want to completely eliminate form your diet. Trans fats occur as a result of hydrogenation and are man made. However, a small amount is found in animal sources but thy do not seem to show the same affect as fats that go through hydrogenation. Trans fats lower HDL (this is the good cholesterol) and increase LDL (this is the bad cholesterol). Due to the high risk of disease associated with these types of fats they were removed from our diets for the most part. We do still have partially hydrogenated oils and things that contain less than 2% of trans fats.


Polyunsaturated and monounsaturated fats are considered “healthy” fats that help lower LDL (bad cholesterol) and reduce ones risk for heart disease. Examples include vegetable oils, avocados, nuts, and seeds.


Omega 3 fatty acids and omega 6 fatty acids are essential fatty acids that we need to consume through our diet. Omega 3’s help with anti inflammation while omega 6’s are going to be pro inflammation. However, both are essential. Omega 3 fatty acids can be found in fatty fish, flaxseeds, and there is a little bit in oils.


The Role of Fats During Exercise


Fats are the primary source of energy during low/moderate intensity exercise as well as long durations of exercise. However, although we use fats we are also still using carbohydrates for energy. When exercise intensity is lower we use fats to ensure that glycogen stores are not depleted so when exercise intensity increases we have enough carbohydrates to sustain the high intensity exercise. If you’re confused that’s okay, exercise metabolism is not black and white. The main point is you use both carbohydrates and fats during exercise.


Using fat as energy during exercise does not equal burning fat. The idea of burning fat is called fat oxidation. But it does not equal fat loss. If you are in a caloric deficit you will not lose weight. Exercise can contribute to you being in a calorie deficit but you need to stay in a deficit throughout the day. There are a few things that improve our ability to essentially burn fat. Exercising is going to improve your metabolism which is going to help our body’s ability to use fat as energy during exercise. Your level of conditioning is going to affect how your body uses fat. Endurance training increases the amount of fatty acids that are stored in muscles which then is going to increase the amount of fat used for energy because fatty acids supply fuel in the muscles. Training increase the size of muscle cell mitochondria which results in fatty acids ability to produce ATP (energy). Training also increases enzymes that help fatty acid oxidation. Basically, muscles that are well trained are going to use more fat for energy compared to muscles that are not well trained. This is going to allow the sparing of glycogen (the storage form of carbohydrates) to be used later.


How Much Fat Do We Need


25-30% of your diet should come from fats. Consuming lower than 25-30% can result in an inadequate consumption of calories, essential fatty acids, and fat soluble vitamins which can result in negative exercise performance and negative health benefits.