Caloric requirements are only the starting point for healthy diets. The quality of one's diet is at least as important as the quantity. In order for parents to provide teens the knowledge and information they need to make healthy food choices, parents themselves must become somewhat familiar with the basics of good nutrition.
Food provides human beings with the essential nutrients that are needed to sustain life. The essential nutrients for humans are: proteins, carbohydrates, fats and oils, minerals and vitamins, and water. Foods that are high in these essential nutrients are considered high quality foods or nutrient dense. These essential nutrients serve three primary functions: 1) to provide the body energy, 2) to promote the body's healthy growth and development, and 3) to regulate the body's functioning. However, only proteins, carbohydrates, and fats and oils, meet the first function; i.e., to provide the body energy (fuel) via the provision of calories. There are both high quality, healthy sources of these energy-providing nutrients, and low quality, unhealthy sources of these nutrients. In order to develop and maintain optimal health, the majority of food in one's diet should come from these high quality sources of nutrients. Thus, not only do adolescents need to eat the right amount of food, but they also need to eat foods which contain the right type of nutrients, and in the right proportions. Although these dietary principles apply to everyone, dietary considerations are particularly important for adolescents due to rapid physical growth that occurs during this developmental period.
The first type of energy-providing essential nutrients is protein. Proteins are nutrients that build and repair body tissue and are particularly important for the development of muscle mass in growing bodies. However, proteins have other important functions including brain development and brain functioning. In general, youth need between 5 to 7 ounces of protein a day, depending upon their overall daily caloric need. There are both animal and plant sources of proteins. Healthy, high quality animal sources of proteins include: fish, eggs, and lean meats low in saturated fats such as chicken, turkey, and lean cuts of beef and pork. Some dairy products are also good sources of protein such as reduced-fat cheeses (1 to 2 ounces). Plants can also provide high-quality, economical sources of proteins. Legumes (beans) are a good source of protein such as kidney beans, chickpeas (garbanzo beans), peanuts (a legume, not a nut), white beans, black beans, as well as soybeans and soy products such as tofu, to name but a few. Nuts and seeds (particularly lentils and quinoa) are other good sources of plant protein. However, it may be surprising what a one-ounce portion of protein actually looks like. One egg, one tablespoon of peanut butter, ¼ cup of cooked beans, and ½ ounce of nuts all equal one ounce of protein. Teens can learn to estimate their serving sizes without actually weighing their food. For instance, a three-ounce portion of meat is approximately the same size as a deck of playing cards.
Carbohydrates are the second type of energy-providing essential nutrients and the most efficient form in this regard. Carbohydrates meet the body's immediate need for fuel to perform many functions such as moving, thinking, and learning to name but a few. In recent years, carbohydrates have earned an undeserved, bad reputation. Without carbohydrates the human body will eventually consume its own muscles to produce the energy it needs and if allowed to continued, we would die. Healthy high-quality carbohydrates are found in whole grains, fruits, and vegetables. Grains are the most calorie dense form of carbohydrates followed by fruits, and then vegetables. While everyone needs some carbohydrates to have enough energy to fuel the body, carbohydrates are not all created equal. For instance, sugar, carrots, and whole wheat bread are all carbohydrates. However, whole wheat bread and carrots are vastly superior to sugar because they contain other vital nutrients and fiber; i.e., they are nutrient dense. Therefore everyone needs to make smart choices about which carbohydrates to eat.
In general, teens need between 5 and 10 ounces of grains each day, depending on their overall caloric needs. In general, one ounce of bread is one slice of bread; one cup of breakfast cereal; or ½ cup of rice, pasta, or cooked cereal. The majority of adolescents' grain intake should be whole grains. Whole grain food products are a higher quality source of grains than refined, processed grains because whole grains provide more fiber and contain other essential nutrients (vitamins and minerals). While not technically a nutrient, fiber is important because it enables the body to metabolize carbohydrates more slowly so youth will feel full longer and will have more steady, even supply of energy. The process of refining grains removes the outer shell or bran from the grain, thus reducing or eliminating the natural fiber. Processed, refined grains include foods like white rice, white bread, white pastas, and many cold breakfast cereals made from refined grains. High quality, healthy whole grains include whole-wheat and other whole grain breads, whole-wheat pastas, oatmeal (not instant), barley, and long-grain brown rice.
Fruits and vegetables are another high quality source of carbohydrates that are nutrient dense; i.e., they contain many essential nutrients (vitamins and minerals), and are a good source of fiber. Unfortunately, few youth get enough fresh produce in their daily diet, especially vegetables. Only 13.8% of high school youth report eating the recommended amount of vegetables daily (Eaton, Kann, Kinchen, et al., 2010). In general, youth need 2 to 4 cups of vegetables daily. A one-cup serving of vegetables is about the same as one cup cooked or raw vegetables, 1 cup of vegetable juice, or 2 cups of leafy raw greens. Teens should try to eat a wide variety of colors and types of vegetables to ensure they get all the nutrients they need. As a general guideline, the darker or more vibrant the color, the more nutrients it contains. Dark green and orange vegetables such as spinach, kale, sweet potatoes, and carrots are all good picks. As well, vegetables should be eaten raw or lightly steamed whenever possible because excessive heat can destroy many of the essential nutrients found in vegetables. Fresh or frozen vegetables are usually a better choice than canned vegetables because heat during the canning process can destroy essential nutrients.
Like vegetables, fruits are a high quality source of carbohydrates that are nutrient dense but they are also more calorie dense. In general, teens need 1 ½ to 2 ½ cups of fruit a day, and only 33.9% of your report consuming enough fruit daily (Eaton, Kann, Kinchen, et al., 2010). One cup of fruit equals roughly one cup fresh fruit, one cup canned fruit, 1 cup 100% fruit juice, or ½ cup dried fruit. The brighter-colored fruits tend to have more nutritional value. Strawberries, blueberries, bananas, kiwis, and oranges are all wonderful sources of vitamins, minerals, and fiber. Fresh fruits also have fiber that can be absent from fruit juices or other processed fruit products. As well, fruit juice products, canned fruits, and dried fruits often contain added sugar which offers little nutritional value.
Fats and oils are the third type of energy-providing essential nutrients and the most calorie dense form. Fats are essential because certain vitamins are fat-soluble meaning they can only be absorbed and transported in the body via fat molecules. Fats also help to protect our immune system, help to maintain a proper body temperature, and help to maintain healthy cellular functioning. Because fats are so calorie dense, only a small amount is needed for optimal health. Adolescences need approximately 5-10 teaspoons a day, depending on their overall caloric needs. Like carbohydrates and proteins, there are high-quality, healthy fat choices, and low-quality, unhealthy choices. Saturated fats (found primarily in animal sources of proteins), and trans fat (found in many packaged food products such as crackers, cookies, cakes) are generally considered unhealthy and should be limited or avoided altogether. Healthy fats (monounsaturated and polyunsaturated fats) are those fats that promote neurological and cardiovascular health. These healthy fats are found fish, particularly wild salmon; vegetable oils, particularly olive and canola oils; and nuts and seeds.
You may recall at the beginning of this section we mentioned that vitamins and minerals are considered essential nutrients along with proteins, carbohydrates, fats, and water. In a healthy, varied, and balanced diet, grains, fruits, and vegetables provide these vitamins and minerals. However, calcium is a mineral that deserves special mention because it is particularly important for adolescents to receive adequate amounts of calcium. During these years of rapid growth and development, the body needs calcium to build strong bones and teeth. As well, teenage bones and the bones of young adults still absorb calcium like a sponge. An adequate amount of calcium during these critical periods is believed to reduce the risk of developing osteoporosis later in life. On average, teens need 1300 milligrams of calcium each day, which equates to about 3 cups of dairy products. Dairy products are a very good source of calcium but also contain high levels of unhealthy, saturated fats. Therefore, dairy products should be fat-free or reduced-fat products. One cup of dairy equals one cup of milk, one cup of yogurt, 1.5 ounces of natural cheese, or 2 ounces of processed cheese. One ounce of cheese is about the same size as four playing dice. While dairy products are perhaps the most common way to get adequate calcium there are also plant-based sources of calcium particularly broccoli, spinach, almonds, figs, oranges, and papaya.
The last and perhaps most critical of the essential nutrients is water. The blood, muscles, lungs and brain contain a lot of water. In fact, it is estimated our bodies are composed of approximately 70% water and we will die much more quickly without water than we would without food. Water transports nutrients, protects the joints and organs, is necessary for the elimination of waste, and helps to maintain core body temperature. Teens should be drinking water throughout the day. However, many youth receive the water they need in the form of sweet drinks such as juice, soda pop, so-called sports drinks, or other sweet beverages. By decreasing their consumption of plain, healthy water they increase their consumption of unhealthy amounts of sodium (salt) and sugars in all its various forms (sugar, corn syrup, fructose, etc). In order to encourage your teen to get enough water, it should be convenient and readily available. It is often simpler to pop open a nice cold can of soda, than to get a glass, fill it with ice, and then fill it with water. A glass of water is also not particularly portable. A healthy and environmentally-friendly option is to buy several plastic water bottles with caps and to re-fill them with tap or filtered water and store them in the refrigerator. These bottles can be carried to school, to sports practice, or consumed on-the-run. As we will see in the next section, the key to making healthy choices is often as simple as making healthy options convenient and readily available.