Importance of Macronutrients

The three main Macronutrients are carbohydrates, proteins, and fats.

Carbohydrates - Carbohydrates provide immediate energy; they are the body's main source of fuel. At each gram, they provide 4 calories. According to the Dietary Reference Intake published by the USDA, a rang of 45-65% of our caloric intake should be from carbohydrates. Carbohydrates are essentially sugar molecules arranged in different ways. There are three main types of carbohydrates: sugar, starch, and fiber. Starches and fibers are chains of sugar molecules (complex carbohydrates), which are later broken down to be used as energy. These three groups are separated by their molecular composition and glycemic index.

          The glycemic index classifies carbohydrates based on how quickly and how high a food will spike blood sugar in comparison to pure glucose. The higher the glycemic index, the quicker blood sugar rises. Factors that may affect a food's glycemic index include: processing, type of starch, fiber content, ripeness, fat/acid content and physical form.

          Although fiber is a subset of carbohydrates, it is very different from sugar and starch. Sugars and starches are broken down by our digestive system into sugar molecules which can either be stored, or used immediately as energy. Fiber is an exception - it can't be broken down into sugar molecules. Fibers pass through our body undigested, but they bind to fatty substances. In result, eating at least 20 - 30 grams of fiber per day can lower bad cholesterol.There are 2 types of fiber: soluble fiber (which dissolves in water) and insoluble fiber. Insoluble fibers help regulate the digestive system, and prevent constipation.

          Some kinds of carbs are better than others. A common myth is that any type of carbohydrate is bad for you - this isn't true. In fact eating a variety of "good" carbohydrates can lower your risk of heart disease by 30%, lower risk of type 2 diabetes, and many other chronic diseases. Examples of "good" carbohydrates include whole grains/whole wheat, beans, brown rice, whole oats, and bulgur.

Proteins - Proteins are large compounds made by combining amino acids. Usually 20 amino acids are used to create a protein, this is a complete protein. When a protein has less than 20, it is considered to be incomplete. Having a complete protein ensures that you are getting the right amount of amino acids that your body needs.

          Your body needs a certain amount of protein to be “healthy” because they are used for a variety of things. One of the main functions of proteins is to contribute energy (calories) to the body. Each gram of protein usually contains 4 calories. Other functions are to transport molecules around our body and create enzymes that help with our energy level and metabolism.

          All humans need oxygen which is a molecule transported around the body. The amount of oxygen you use depends on the physical activity you’re doing. Anaerobic activities require more oxygen while aerobic activities require less. Oxygen is transported in a protein called hemoglobin. Hemoglobin in the blood carries oxygen from the respiratory organs to the rest of the body. This results in the oxygen burning nutrients to provide needed energy. The process of getting our energy from food is called metabolism. Certain proteins cause chemical reactions that convert the fuel from food into the energy we need, and oxygen is only one of these.

          The proteins we get come from the food we eat. The recommended amount of protein for an average teen is about 10-35% of your daily caloric intake. The average amount of proteins for girls (ages 14-18) is about 46g, and the average amount of proteins for boys (ages 14-18) is about 52g. However this amount changes depending on your activity level and growth. Sources of good protein are meat products (hamburgers, fish, chicken), dairy products (cheese, milk, yogurt), eggs, tofu, lentils, and soymilk.

Fats - Fats are molecules made of lipids. These molecules are usually stored for longterm energy. Once the energy received from carbohydrates is used up, the body resorts to using fat as an energy source. There are three different major types of fat. Trans fat and unsaturated fat are fats that are bad for you because they increase your body's LDL (bad cholesterol) and also increase the risk for heart disease. Unsaturated fat is supposed to be healthier and examples of these are olive oil and canola oil. Foods like Avocados are also healthy because they contain fatty acids which the body needs.