Nutrition Tuesday: Fats Aren’t Evil!


Fats seem to be a dirty word to many people. Before the low-carb focus in diet trends, dietary fat was the primary target of public and academic condemnation. It is important, especially for athletes, to understand the basic chemistry of fat (not all fats are created equally!) and the metabolism of fat. First, let’s look at some definitions to clear up the air about evil fats…

Lipids – A class of molecules that are composed of triacylglycerols, sterols, and phospholipids.
Triacylglycerol (also called triglyceride) – A glycerol “backbone” molecule with three fatty acids. One gram of triacylglycerol (TAG) provides 9 kcal of energy to the body when utilized.
Glycerol – A three-carbon molecule that is “backbone” of TAGs. By itself, glycerol is a “sugar” and when released from storage, it can be recycled by the liver to create new blood glucose.
Fatty acids – Chains of carbon atoms of various lengths that attach to a glycerol molecule to form TAGs. A fatty acid with no double bonds is called a saturated fatty acid. A fatty acid with one double bond is called a monounsaturated fatty acid and a fatty acid with two or more double bonds is called a polyunsaturated fatty acid.

An example of an unsaturated TAG

Fats are interesting in how they are stored in the body. Once fats are digested, they are packaged into chylomicrons, which are lipoprotein particles that transport dietary fats from the intestines to other parts of the body1. Once the digested fats have reached their targeted cells, they are either stored or used depending on the person’s physiological state. The infamous “fight or flight” hormones (i.e. adrenaline) and muscular contractions (only up to a certain point though) induce fat breakdown and burning in the processes called lipolysis and oxidation. If the body is in the “restive-digestive” state, the hormones secreted during this stage and the relative lack of muscular activity induce fat building/storage called lipogenesis1
Dietary fats are physiologically different than other major micronutrients because fatty acids can be incorporated into the phospholipid bilayer of the cell membrane, which ultimately can lead to membrane fluidity changes and different physiological effects of the body, such as inflammation or blood clotting. What is the phospholipid bilayer of the cell membrane you ask? Well, think back to your high school biology days… okay, depending on your age, your biology book might not have covered the phospholipid bilayer. In a nut shell, a phospholipid bilayer is a think polar membrane made up of two layers of lipid molecules. Cell membranes of almost all living organisms and many viruses are made of a lipid bilayer. It serves as a barrier to keep ions, proteins, and other molecules where they need to be and prevent them from “running away.” Phospholipids have a “water-loving” head and a “water-hating” tail. Thus the “water-loving” heads face out and the “water-hating” tails always face inward. And that’s all you really need to know about that, but I could go on for days about the topic.

Here’s a nerdy video of the plasma membrane 🙂
Certain fatty acids are known to be essential, sort of like certain amino acids, because the human body is unable to create them in the body; thus, these fatty acids must be obtained through diet. These essential fatty acids are called linolenic (Omega 3) and linoleic acid (Omega 6). 
Omega-3 and omega-6 fatty acids are important in the normal functioning of all tissues of the body. Adequate intake of these essential fatty acids have shown in studies to help prevent atherosclerosis, reduce the incidence of heart disease and stroke, and reduce joint pain among other things2

Stored cellular fat in the form of TAG is the primary fuel source during fasting periods lacking intense physical exertion1. Research has shown that about 60% of a human’s “fuel mix” at rest – in a fasted state- is from fat1. So, now you think you can become a couch potato and burn fat! Sounds great doesn’t it? But, that’s not how it works. Just sitting there on the couch and watching television requires very little caloric expenditure and thus “60% of nothing is still nothing!”1 So get off your butt and start moving!
The use of fatty acids during physical activity is an interesting relationship. A couple weeks ago I discussed metabolism. If you need a review, click HERE. There is a direct relationship between fat use and exercise duration. The longer you exercise at a low-moderate pace (i.e. your endurance pace and/or Zone 2 heart rate), the greater your fat breakdown and “burning.” However, there is an inverse relationship between fat use and intensity. The more intense you exercise, the less stored fat can contribute (i.e. your body switches to mainly carbs). 
It is important to include healthy fats (i.e. monounsaturated and polyunsaturated fats) and in your diet because fats serve the following functions in your body:
  • Fat is used by your body for fuel because it is the most energy-dense macronutrient and they provide most of the body’s tissues and organs (including your heart!) with their energy1
  • Cell membranes are composed of phospholipids
  • Fats are critical for the transmission of nerve signals that generate muscle contractions1
  • Serve as a transporter for vitamins A, D, E, and K1
  • Provide cushioning for the protection of vital organs and insulation from cold environments1
  1. Antonio J, et al. Essentials of Sports Nutrition and Supplements. Totowa, NJ: Humana Press, 2008.
  2. Physicians Committee for Responsible Medicine. Essential Fatty Acids. Available at: Accessed June 4, 2012.   
(Disclaimer: Once again this is for your information only. If you feel you need help with your diet and health then I urge you to seek professional medical and nutrition advice from an expert.)

Nutrition Tuesday: Overview of Macronutrients and Micronutrients

Last week we discussed the basics of metabolism. Now it’s important to discuss what nutrients fuel the body to not only get us through exercise, but our day-to-day activities for survival. Our bodies require two different types of nutrients: macronutrients and micronutrients. 
Macronutrients are carbohydrates, fats, and proteins, which ultimately provide the energy necessary to maintain body functions at rest and during physical activities and maintain the body’s structural and functional integrity1
Micronutrients are vitamins and minerals. As their names imply, macronutrients comprise most of a person’s dietary intake, while micronutrients are essential in much lower quantities. With the deficiency of micronutrients, athletic performance in addition to normal physiologic function will suffer. However, with a well-balanced diet, a person should not have to worry about any imbalances. 
Today’s post will give an overview of each type of nutrient required by the human body. The next few days this week I will post a more in-depth look at carbohydrates, fats, and proteins. Next week I will discuss vitamins and minerals.
The Macronutrients
Carbohydrates often get a bad name, but without question, wholesome forms of carbohydrates are the best choices for fueling your muscles and promoting good health. Carbohydrates, as their name suggests, are carbon-, hydrogen-, and oxygen-based molecules that are abundant in most plant foods, especially fruits and grains1. Not all forms and sources of carbohydrates are alike. The carbohydrate family includes both simple and complex carbohydrates2. Simple carbohydrates are monosaccharides (structurally the simplest form of carbohydrates) and disaccharides (two monosaccharides). Glucose, fructose, and galactose are monosaccharides or sometimes referred as the simple sugars2. The three most common disaccharides are sucrose (table sugar), lactose (milk sugar), and maltose (malt sugar)2
Complex carbohydrates are formed when sugars link together to form long complex chains, similar to a string of pearls. Plants store extra sugar in the form of starch, which is a complex carbohydrate. Humans store extra glucose mostly in the form of muscle glycogen and liver glycogen. This glycogen will become available for energy during exercise. 

The main functions of carbohydrates are:
  • The primary function is to provide energy to the cells of the body, particularly the brain
  • Facilitate the body’s metabolism of fat
  • Spare muscle protein
Lipid is the collective name given to a vast variety of water-insoluble chemicals, including fats and oils. Fat or lipids are made up of carbon, hydrogen, and oxygen atoms. The ratio of oxygen to carbon and hydrogen is much lower in lipids than in carbohydrates, and thus lipids are a more concentrated source of energy1. There are three major types of fatty acids that can be distinguished by their molecular bonds and number of hydrogens. Fats can be saturated (the maximum number of hydrogens), monounsaturated (having one carbon-carbon double bond), or polyunsaturated (having two or more carbon-carbon double bonds)1

The main functions of fats:
  • Fats provide many of the body’s tissues and organs (including the heart) with most of their energy. Fat is the ideal fuel because it contains almost twice the energy as glucose, weighs less, and is easily transported and stored1.
  • Essential for the transmission of nerve signals that generate muscle contraction.
  • Serve as a transporter for vitamins A, D, E, and K.
  • Provide cushioning for the prevention of vital organs and insulation from thermal stress of cold environments.
Proteins are essential nutritionally because they are comprised of amino acids, which the body needs to synthesize its own proteins and nitrogen-containing molecules that make life possible1. Amino acids are the building blocks of proteins. There are 20 amino acids. Of these 20 amino acids, 9 are considered to be essential because the human body cannot synthesize these amino acids. The remaining 11 amino acids are considered nonessential because the human body can synthesize them. 

The main functions of proteins:
  • Produce antibodies for the immune system
  • Produce enzymes that are required for various chemical reactions in the body
  • Component of structural hormones:
    • Contractile proteins for muscle tissue (i.e. actin and myosin)
    • Fibrous proteins in connective tissues (i.e. collagen, elastin, and keratin)
  • Component of transport proteins (i.e. hemoglobin)
  • Component of peptide hormones (i.e. insulin, thyroid hormone, etc.)
  • Source of fuel when muscle glycogen levels are low due to prolonged intense exercise 
The Micronutrients
Vitamins are metabolic catalysts that regulate biochemical reactions within the body2. They are found in plants that we eat and are created by the plants themselves. Vitamins are categorized into either water-soluble or fat-soluble vitamins. Water-soluble vitamins are found in the fluid portion of our bodies and do not accumulate to a large degree in the body1. Fat-soluble vitamins are stored in the lipid (fat) portion of our bodies and can accumulate in the cells1. Some vitamins include: Vitamin B6, Vitamin C, Vitamin D, and Vitamin A.
Minerals are natural substances that plants must absorb from the soil2. The human body uses minerals for many different jobs, including building bones, making hormones, and regulating the heartbeat. There are two kinds of minerals: macrominerals and trace minerals3. Macrominerals include calcium, phosphorus, magnesium, sodium, potassium, chloride and sulfur3. Trace minerals include iron, manganese, copper, iodine, zinc, cobalt, fluoride and selenium3

  1. Antonio J et al. Essentials of Sports Nutrition and Supplements. Totowa NJ: Human Press, 2008.
  2. Clark N. Nancy Clark’s Sports Nutrition Guidebook, 4th Ed. Champaign, IL: Human Kinetics, 2008.
  3. MedlinePlus. Minerals. Available at: Accessed May 28, 2012. 
(Disclaimer: This is for your information. If you need help with your diet and developing healthy lifestyle choices then I suggest seeking out professional help from your medical professional or registered dietitian. If you see any errors, please let me know!)