The Macronutrients: Carbohydrates, Protein, and Fat
As athletes we are constantly asking ourselves about The Macronutrients: Carbohydrates, Protein, and Fat, the role they play in our diets and how they affect our body during athletic performance. I will try to take some of the mysteries away from Carbohydrates, Protein, and Fat with some simple explanations of each.
Usually when we are talking about Carbohydrates, Protein, and Fat we are talking about “what to eat” or basically plain old food. Food is thought of as the things we eat that are made up of macronutrients that include: Carbohydrates, Protein, and Fat; along with micronutrients such as vitamins, minerals, and trace elements. For detailed information about vitamins and minerals see my article “Vitamins and Minerals for Athletes”. Let’s take a look at the macronutrients (meaning the body needs them in large quantities) in detail.
Carbohydrates are a dietary compound that is found in most foods which includes sugars, starches, and fiber. The body breaks down carbohydrates into simple sugars (fuel) for use by your body’s cells and muscles, and this is the primary source of energy for the body. Your brain, heart, muscles, plus various vital organs all need carbohydrates. The main fuel for the brain and the central nervous system is glucose which is easily obtained from carbohydrates. Carbohydrates contain 4 calories per 1 gram.
Carbohydrates can be broken down into three groups: 1) Disaccharides , 2) Polysaccharides, and 3) Monosaccharides.
Technically, Disaccharides are formed by two monosaccharides linked by a glycosidic bond. Disaccharides are carbohydrates that are found in such things as table sugar (sucrose), maltose (malt sugar) , and lactose (the sugar found in milk). They provide a sweet taste to food and give you relatively quick energy. Disaccharides are important because they can be hydrolyzed into important monosaccharides (such as glucose). Glucose is very important as a energy source and are the building blocks for polysaccharides.
Polysaccharides are commonly known as complex carbohydrates which consist of starches and fiber. Complex carbohydrates play a major role to maintain blood sugar levels and provide a constant source of energy. They are formed by repeating units of Monosaccharides or Disaccharides and are the largest of the carbohydrates. Polysaccharides typically contain hundreds of monosaccharides connected together in various ways. There are two types of Polysaccharides 1) Storage Polysaccharides which come in the forms of starches and starch-like sugars such as: dextrin, pectin, and glycogen, and 2) Structural Polysaccharides which come in the forms of cellulose and chitin. Food sources for Polysaccharides are: whole grains, vegetables, nuts, fruits, flaxseeds, pumpkin seeds, potatoes, corn, legumes, and root vegetables just to name a few.
Fiber is a compound that only plants contain, you will never find it in any meats. Fiber is found mainly in fruits, vegetables, whole grains and legumes. Although fiber does not provide the body with any energy, it does play a role in many health benefits. Some of these benefits include, relieving constipation and hemorrhoids, weight control, and preventing disease. Some of these diseases are: heart disease, cancer, diabetes, gallstones, and kidney stones. The fiber that we consume in our diet is called dietary fiber.
Dietary fiber is often referred to as roughage. Roughage is the indigestible portion of the plant food that your body cannot digest or absorb. This bulk of roughage passes relatively intact through your stomach, small intestine, colon and out of your body. It helps with the intestines in working efficiently and helps regulate the even absorption of sugars into the blood stream. Dietary fiber has two components: 1) Soluble Fiber, and 2) Insoluble Fiber.
Soluble fiber dissolves in water to form a gel-like material. Soluble fiber helps prolong stomach emptying time so that sugar is released and absorbed more slowly. It can help lower blood cholesterol and glucose levels.
Soluble fiber is found in such foods as: oats, dried beans, nuts, vegetables such as carrots, oranges, peas, beans, apples, citrus fruits, barley and oat bran.
When we talk about roughage we are talking about insoluble fiber. Although it does not dissolve in water, it does absorb it and this helps increase the bulk of the fiber. Insoluble fiber aids in the movement of material through your digestive system and increases stool bulk. By consuming these types of fiber, the amount of time that digested food sits in the intestines is decreased. This action helps keep the body from absorbing starch and sugar in the intestines. It also aids removing toxic waste through colon in less time.
Insoluble fiber can be found in foods such as: Whole-wheat flour, corn bran, fruit skins, root skins, dark leafy green vegetables, wheat bran, nuts and many vegetables.
Monosaccharides (from Greek monos: single, sacchar: sugar) are simple sugars like glucose and fructose and they are the predominates carbohydrate absorbed in the digestive tract. The body however can only absorb monosaccharides which means that disaccharides and polysaccharides must be digested into monosaccharides before they are absorbed. Once they are digested they are absorbed through the small intestine and then circulate into the bloodstream through the liver as blood glucose. Our body uses glucose in three ways.
1) It can use glucose for immediate energy.
2) If it is not needed for immediate energy the glucose is converted into glycogen in the liver and muscles. Only the glycogen stored in the liver can be made accessible to other organs, while muscles have the necessary enzymes to convert glucose into glycogen within the muscle.
3) If the body has enough glucose, and the glycogen levels are full; the excess glucose is converted to fat by the liver and stored as body fat around the body. It is important to note that fat cannot be turned back into glucose.
Protein is an important component of every cell, tissue, and organ in our body. One of the main functions of protein is to synthesize proteins like muscle and hormones such as: insulin, growth hormones, and Insulin Growth factor I. These hormones can affect and influence many functions in the body such as muscle growth, recovery, and the absorption of nutrients into your muscles.
Protein is an important building block of bones, muscles, cartilage, skin, and blood. Even your hair and finger nails are mostly made of protein. In our body protein is constantly being broken down and replaced. The way these proteins are replaces is by the by the foods we eat through their digestion into amino acids. The body is in a constant state of repairing and replacing cells, and this is accomplished by the body protein constantly being turned over as old cells die and new cells replace them. All these new cells come from protein. For protein synthesis to occur, an adequate supply of both essential amino acids and non-essential amino acids is crucial. If even one amino acid is missing synthesis will come to a stop. Unlike fat and carbohydrates, the body does not store protein; and therefore has no reservoir to draw on when it needs a new supply. This is why it is essential to eat smaller meals through the day to keep your blood sugar stabilize in a positive anabolic state. When you go for several hours without eating protein your body will enter a catabolic muscle-wasting state. In other words, your body is eating itself to supply it with the amino acids it requires for functioning properly. Protein contains 4 calories per 1 gram.
The Characteristics of Protein
As stated above, when we eat proteins they are digested and converted into amino acids. Protein is made up of Amino acids and they are the building blocks of proteins and act as intermediates in metabolism. The body is only capable of producing 10 of the 22 amino acids; the others must be supplied in the food. It is essential that we get the proper foods to fulfill all of the protein and amino acid needs that our body need to function properly. As stated earlier, the body cannot store protein; hence it cannot store amino acids. Therefore, when there is a lack in a needed amino acid, the body will start to eat itself to obtain the amino acid that it needs. The 10 amino acids that we can produce are alanine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine and tyrosine.
Amino acids are categorized as: 1) Essential, 2) Conditionally-Essential, and 3) Non-Essential.
1) Essential: These are the ones that cannot be produced in the human body and must be obtained by food. There are 8 essential amino acids, these include: isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
2) Conditionally-Essential: Some non-essential amino acids in adults are essential in infants, and others become essential when there are conditions in the body that prevent the biochemical conversion of one amino acid into another. There are 7 conditionally-essential amino acids which include: cysteine, glycine, glutamine, histidine, proline, serine and tyrosine.
3) Non-Essential: These are made by the body from the essential amino acids or normal breakdown of proteins. The non-essential amino acids are: arginine, alanine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, proline, serine, and tyrosine.
Of the amino acids there is a group called the Branch Chain Amino Acids (BCAAs): Leucine, isoleucine, and valine. They are called branch chain amino acids because the human body cannot survive unless these amino acids are present in the diet. The combination of these three amino acids makes up approximately one-third of skeletal muscle in the human body.
It is important to note that just because amino acids are classified into basically two categories of essential and non-essential, all 22 of them are required for health.
The biggest benefit of fat is that it make our food taste great. Who doesn’t like bacon-wrapped shrimp? Okay, maybe the wrong kind of fat for a healthy lifestyle. As much as we try to cut fats out of our diets they are essential for good health. Fats are our body’s secondary source of energy when we are competing in an event and during training. When our carbohydrates stores in out muscles are depleted fat-based energy becomes available. Although carbohydrates are our body’s major source of energy, fats are the most highly concentrated source of energy.
Other than energy, fat provides many benefits to good heath. Fat is essential for healthy hair and skin, and every single cell contains essential fatty substances in their membranes. Fat acts as a carrying agent and is needed so your body can absorb the fat soluble vitamins A, D, E, K, and prevent deficiencies of these vitamins. It also protects our organs and the layer of fat underneath our skin keeps the body warm and generates heat. Fat helps food to stay in the stomach longer, giving a greater sense of satisfaction and prevents hunger soon after meals. Fat provides essential fatty acids that the body cannot produce. Fat also helps regulate the cholesterol in your blood. However, it is important to monitor the types of fats that we eat in our daily diets. Fat contains 9 calories per 1 gram.
Types of Fats
While it is true that we do need fats in our diet for proper health, some fats are damaging to the cardiovascular system. These “bad fats” are saturated fat and trans fat. The more heart-healthy fat is unsaturated fat which is generally found in vegetables.
Saturated fats are mainly found in animal products and can be identified as the fats that stay solid at room temperature. Saturated fats (animal fats) raise the levels of LDL cholesterol (the bad cholesterol) in your blood, and they also raise the levels of HDL (the good cholesterol).
Some sources of saturated fats are: whole milk, butter, cream, ice cream, red meat with fat, the skin on chicken, chocolate, cheese, beef, lamb, pork, lard, beef fat, fast foods, coconut oil and palm oil.
Trans fats are the most harmful and damaging fats; even worse than saturated fats. They come from hydrogenated vegetable oils like margarine and vegetable shortening. Like saturated fats, they stay solid at room temperature. Trans fats raise the levels of LDL cholesterol (the bad cholesterol) in your blood, however; they lower the levels of HDL (the good cholesterol).
Trans fats are also known as hydrogenated fats and are names on food labels as “partially hydrogenated vegetable oil” and are found in most margarine, butter, whole milk, shortening, cooking oils, processed foods, snack foods and commercially fried foods.
You should make every effort to eliminate them from your diet.
Unsaturated fats are liquid at room temperature. They include two types 1) monounsaturated, and 2) polyunsaturated.
1) Monounsaturated Fat
Monounsaturated Fat come from olive oil, canola oil, avocados, peanuts, most other nuts, and peanut oil. Monounsaturated fats are a healthiest choice of fats since they lower LDL levels and raise HDL levels.
2) Polyunsaturated Fat
Polyunsaturated fats are considered the next healthiest fats as they can lower blood cholesterol levels, protect the heart, and prevent heart disease. Their source is from soybeans, corn, safflower, and sunflower oils. They are divided into two types: omega-3 fatty acids and omega-6 fatty acids.
Omega-3 Fatty Acids
Omega-3 fatty acids can be found in oily fish such as mackerel, herring, sardines, salmon, tuna, swordfish, as well as in oils such as soy oil and canola oil and spreads made from these oils.
Omega-6 Fatty Acids
Omega-6 fatty acids are found in nuts such as walnuts, Brazil nuts and seeds such as sunflower and sesame seeds. They are also present in corn oil, sunflower oil and safflower oil.