NASM CNC Chapter 8: Fats

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Chapter Goals:

• Explain the functions and the structure of fat.
• Discuss the absorption and digestion for fats in the body.
• Find the requirements for total daily fats.
• Discuss the method for establishing a diet program’s requirements for fats.
• Discuss the hot topics or myths that relate to fat.
• Communicate with your clients regarding guidelines for fat intake, fallacies, and some facts.

Introduction

Fat is one of our three macronutrients we take in within the human diet. This fat is vital for survival, and it has many functions it does in the body. Some of the main functions are providing energy, the metabolization of fat-soluble vitamins, and the act of taking in the essential fatty acids. Fat is different from protein and carbs, due to the fat being hydrophobic and thus, not soluble in water. 

Fats provide 9 calories per gram.

Structure of Lipids

Lipids are made up of repeating fatty acid units. Fatty acids are made up of hydrogen, carbons, and oxygen. There are many different kinds of lipids, and each have a vital role for the body. 

Simple Lipids

Fatty acids are the building blocks of fats. These are made up of long chains of hydrocarbons. One end has a carboxyl group, which is the thing that makes a fatty acid an acid. These can be saturated or unsaturated fatty acids. 

Saturated fatty acids are the fatty acids that have the max amount of hydrogen molecules and have single bonds between the carbons. Food that is high in saturated fats will be solid at room temperature and found oftentimes in the animal fat, in palm oil, and in coconut oil. 

Unsaturated fats are the fats that have at least one double bond between the carbon chains. These are going to be liquid at room temperature, they are not stable, and they are prone to damage from oxidation.

Hydrogenation is the process of making hydrogen into vegetable oil in order to make a semi-solid or a solid saturated fat.

Oxidative damage is the imbalance that happens in free radicals and antioxidants. Free radicals are thing that have molecules with oxygen and an uneven number of electrons, thus making them react more easily with other molecules.

Monounsaturated fats are the unsaturated fats that are only going to have one unsaturated carbon.

Polyunsaturated fatty acids are the unsaturated fats containing at least two double bonds between the carbons.

Monounsaturated fats are vital for a healthy diet for your heart. The Mediterranean diet is an example of a diet that focuses on this. This diet is based on the more traditional foods that people ate in Greece and within Italy. These foods were high in monounsaturated fats and they included the olive oil, seeds, and also nuts.

Trans fat is an artificial fatty acid that is present when hydrogen has been added to liquid vegetable oil in order for them to be made more solid and have a longer and more stable shelf life.

LDLs are Low density lipoproteins. These are known as the bad cholesterol. This takes the cholesterol from the liver and to the cells.

HDLs are high density lipoproteins. This are known as our good cholesterol. These cells work to transport cholesterol from the cells and to the liver. 

The Adipose tissue is our loose connective tissue that is made up of fat cells that we store for potential energy later.

Compound Lipids

The compound lipids we take in are either phospholipids or they are lipoproteins. 

Phospholipids are made up of two fatty acids, one phosphate group, and a molecule of glycerol. The phosphate head is the part that is soluble in water, and the fatty acid tails are insoluble in water. These act to form the cell membranes. 

Lipoproteins are a combination of fats and proteins that act to transport cholesterol and other lipids both to and away from the tissues using our blood.

Hydrophilic is something that loves water and will thus, dissolve in it. 

Function of Lipids

Dietary fats are a required source for essential fatty acids and fat-soluble vitamins. 

Functions of Dietary Fats

Fats as Major Energy Source

Dietary fat provides 9 calories per gram, and this is over two times the amount that both protein and carbs give at 4 calories per gram. The majority of our excess intake of fats is to be stored as triglycerides in the body. When carbs are not available, fat will be used during physical activity.

Fats are a Source for Essential Fatty Acids

Omega-3 and Omega-6 fats are necessary for us to get into the body. We get these through sources like walnuts, flaxseeds, flaxseed oil, and also chia seeds. These two fatty acids provide many benefits for our bodies.

Fats Metabolize Fat-soluble Vitamins

These vitamins that can only really be taken in with fats are the vitamins A, D, E, and K. 

Dietary Fatty Acid Recommendations

Dietary Reference Intakes are the recommended amount to intake of the many nutrients determined by the food and nutrition board. This includes the RDA and AMDR. 

Adequate Intake is the recommended daily average that is based upon the healthy population. 

Function of Fat Within the Body

Cell Membrane Structure and Function

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Cells are encircled by a cell membrane. This membrane is responsible for protecting the inside of the cell and also for selective permeability. The main component of the membrane is actually the phospholipids. These are arranged in a bilayer  in order to keep water in and water out of the cell. 

Insulation and Temperature Regulation

The thin layer of fat under our skin is used for insulating heat and the other fat in our body is used for protecting our internal organs and may act as a cushion of sorts. 

Digestion and Absorption

Most dietary fats are eaten and then stored as triglycerides. These fats need to be broken down into component parts by digestion, transported with the blood, and then delivered to the cells in need. 

The mouth and the stomach

This is always the first step for any macronutrient. We must take the nutrient in through the mouth and we chew and add some phospholipids to function as an emulsifier. The enzyme lingual lipase will break down the triglycerides, thus a separation of the fat from the water soluble parts in food. Swallowing the fat move it to the stomach and here the gastric acids break down the fats. The stomach contracts and churns, thus spreading the fats prior to entering the small intestine. 

Small Intestine

Bile acts as an emulsifier for the fats and is released here when the fats enter. Micelles are formed from the bile salts surrounding the monoglycerides. The fats then move to transport and storage in the body. 

Transport and Storage

Transport of Lipids

When the monoglycerides, the fatty acids, and the fat-soluble vitamins reach the small intestine, they essentially reassemble into triglycerides. These are then going to enter into the lymphatic system and move to a large vein that drops to the heart. 

Liver

LDLs and HDLs are going to come into play here. These two acts to deliver and bring back the cholesterol in the body to and from cells. 

Fat Metabolism and Storage

The chylomicrons and the VLDLs deliver the triglycerides to the cells, which are broken down and the glycerol used by the cell. Fatty acids are combined with glycerol to form a triglyceride in order to store in the body. Triglycerides go through beta-oxidation in the cells and the byproducts are free fatty acids and glycerol. In muscle cells, the free fatty acids may be stored, or they might get made into acetyl-coA. Acetyl-coA is used in chemical reactions in protein, carbs, and lipid metabolism. 

Dietary Fat Recommendation and Programming

Dietary Fat and Saturated Fat Recommendation

There are many organizations that have made recommendations for dietary and saturated fat. 

Translating Recommendations into Food Choices

Dietary Essential Fatty Acid Recommendations

The AI for omega-3 is around 2.6 grams for males and 1.1 grams for females.

The AI for Omega-6 is 17 grams for males and then 12 grams for women. 

Programming

Dietary fat is an essential part of our diet, and it is vital that we program the appropriate amount for the plan we wish to follow.