What kinds of food provide you with energy?

            The foods that are the best sources of energy are those that contain large amounts of carbohydrates and fats. When these foods are chemically changed in your cells, large amounts of energy are released.
            Carbohydrates are compounds of three elements – carbon, hydrogen, and oxygen. Starch is one common carbohydrate. Grains such as wheat, corn, oats, rye, and rice are mostly starch. So foods made from grains are very rich in starch. Some of these foods are breakfast cereals, bread, crackers, spaghetti, macaroni, and noodles. Potatoes, dried beans, and dried peas also contain much starch.
            Sugars are also carbohydrates. The sugar that you are probably most familiar with is sucrose. This is the sugar that we ordinarily use to sweeten our food and for cooking. Candy, honey, molasses, fruits, and berries have much sugar in them. Milk contains much lactose, or milk sugar.
            Two common simple sugars are glucose and fructose. They are found in the sap of plants and in the juice of fruits. Simple sugars are the only carbohydrates that your cells can use. All the more complex carbohydrates must be changed into simple sugars. This is one of the changes that takes place when carbohydrates are digested.
            Fats are also compounds of carbon, hydrogen, and oxygen. Fats provide more energy than any other food. Your body gets more than twice as much energy from an ounce of fat as from an ounce of sugar. However, fats are usually more expensive and are not so easily digested.
            All greasy and oily foods contain fats. An oil is a fat that is liquid at ordinary temperatures. Cottonseed oil, corn oil, peanut oil, soybean oil, olive oil, coconut oil, and fish-liver oil are liquid fats. Fat meat, egg yolks, nuts, cream, and cheese all contain large amounts of fats.
            Although carbohydrates and fats are important mainly as sources of energy, there are other reasons why your body needs them. Carbohydrates provide food for tiny bacteria that live in your intestines. These bacteria make some of the chemicals your body needs. Plants such as lettuce, celery, cabbage, and green beans contain much cellulose. This carbohydrate cannot be digested by your digestive juices. However, it provides the bulk needed to remove waste materials from your intestines. Fats help your body use other foods efficiently. Fats also contain materials that your body needs in very small quantities. The cells of your body also use digested fats as one kind of building material for protoplasm.

What kinds of food provide you with materials?

            Your body needs food to supply it with materials as well as energy. Some of these materials are used by your cells to make protoplasm and other materials that are part of your body. Your cells also use materials to make the chemicals that keep your body working properly. Foods that are rich in proteins and minerals provide your body with many of these materials.
            Proteins are compounds that contain carbon, hydrogen, and oxygen, just as fats and carbohydrates do. But besides these three elements, all proteins contain nitrogen. Most proteins also contain sulfur, and some contain phosphorus. You get most of your proteins from meat, eggs, fish, milk, and cheese. Peas, beans, and some nuts also have large amounts of proteins in them.
            Foods rich in proteins are not used mainly as energy foods. Your body has better uses for them. The cells of your body are made almost entirely of proteins and water. To make new protoplasm, your cells must have proteins. Without proteins, your body cannot grow, repair itself, and keep working properly. Protein-rich foods are often called body-building foods. Your body cannot make proteins from fats and carbohydrates.
            When a food is burned as completely as it can be, only the minerals are left. So chemists often call minerals ash.
            Your body needs fairly large amounts of calcium and phosphorus to make the hard material in your bones and teeth. Calcium also helps your blood thicken, or clot, if you cut yourself. New blood cells must have iron and copper to grow. Your hair and nails need sulfur. A chemical that controls the beating of your heart contains sodium. Chlorine is used to make hydrochloric acid, which is an important part of the digestive juice made by your stomach. Without iodine, the thyroid gland in the front of your neck cannot make its chemical. Lack of iodine may cause a disease called goiter, in which the thyroid gland becomes much enlarged. Potassium, magnesium, manganese, cobalt, fluorine, and other mineral elements are needed in your body, too.
            Minerals provide your body with building materials. However, minerals also supply materials to make chemicals that your body needs. Because these chemicals protect your body and keep it working properly, minerals are sometimes called protective foods. Most people get enough of all the mineral elements except four – calcium, phosphorus, iron, and iodine. Milk and cheese provide calcium and phosphorus, while egg yolk and meats provide phosphorus and iron. Some vegetables contain all three of these elements. Fish, oysters, clams, and other seafood are very rich in iodine. If you do not eat much seafood, you can use iodized salt, which has a small amount of iodine in it.
            Another material that your body must have is water. Water from wells and springs often contains dissolved minerals. But water itself is important to your body. Almost 2/3 of your weight is water. Protoplasm is about 4/5 water. And the liquid part of blood is almost all water. Water helps digest food and is needed for many other chemical changes in your body. It also helps keep your body at the proper temperature and remove waste materials. To stay alive, you must have a constant supply of water. Your body can go without other foods much longer than it can go without water.
            The amount of water you must take into your body depends on how much you have lost. The foods you eat provide you with much of the water you need. Milk, soup, and other liquid foods are mostly water. So are juicy fruits and vegetables such as melons, apples, and tomatoes. Usually you cannot get all the water you need from foods. You should also drink water every day to supply the rest of the water you need.

Why are vitamins important in your food?

            Vitamins are protective foods, too. They are materials that help regulate changes in your body. Certain foods contain special chemicals which we must all have to keep well. If a person does not get enough of some vitamin, he may develop a deficiency disease such as scurvy, beriberi, rickets, or pellagra. A deficiency disease is caused by the lack of some material, usually a vitamin or mineral, in a person’s food. Only small amounts of these materials are ordinarily needed. If you choose your foods wisely, you can usually get all the vitamins and minerals you need in the foods you eat.

What foods should you eat?

            The foods that you eat every day should include the proper amounts of all these things if you are to stay healthy. Your diet should be well balanced. Diet means the kinds and amount of food that a person or an animal eats.
            To help people choose foods that will provide them with all the materials they need, scientists have worked out a Daily Food Guide that is easy to follow. This food guide includes four main groups: (1) the milk group, (2) the meat group, (3) the vegetable-fruit group, and (4) the bread-cereal group. If you eat the right amounts of foods from each of these groups and drink plenty of water every day, you will get all the materials your body needs.
            The milk group includes milk, cheese, and ice cream. Milk is our best source of calcium and is very rich in phosphorus. A quart of milk every day will provide all the calcium and more than half the phosphorus that your body needs. Cheese and ice cream do not contain as much calcium as milk does.
            All kinds of meats, fish, poultry, and eggs are included in the meat group. All these foods are good sources of proteins. They also supply iron and several of the B vitamins. Dried peas and beans, nuts, and peanut butter are also sources of these materials. You should eat two or more servings of foods from the meat group every day.
            The third group is made up of all the fruits and vegetables. You should be especially careful to eat enough of those that provide vitamin C and vitamin A. citrus fruits, cantaloupe, broccoli, fresh strawberries, and peppers are all good sources of vitamin C. dark-green or deep-yellow vegetables and fruits such as spinach, broccoli, carrots, sweet potatoes, and cantaloupe provide much vitamin A. Usually the deeper the color, the more vitamin A the vegetable or fruit provides. You should eat at least four servings of fruits and vegetables every day. One of these servings should be a fruit or vegetable rich in vitamin C. to get enough vitamin A, you should also eat a serving of a dark-green or deep-yellow fruit or vegetable at least every other day.
            Bread, cereals, and other foods made from grains are included in the fourth group. These foods contain large amounts of carbohydrates, which your body uses for energy. They also contain some proteins. Many people prefer bread made from white flour, which has lost most of its vitamins and minerals. To make up for part of this loss, white flour and white bread are usually enriched by adding B vitamins and iron. Cereals are said to be restored when they have been enriched with B vitamins and iron. You should eat at least four servings of foods from this group every day. If you do not eat cereal, you should choose a fifth serving of one of the other foods in this group.
            You will probably want to eat more than just the suggested number of servings in each food group. You will also want to include other foods such as butter, margarine, cream, salad dressing, and different kinds of sweets. Be sure not to eat too many sweets or to eat them between meals. Very small amounts of sweets can satisfy your hunger without providing you with all the materials you need.

How much food should you eat?

            Eating food from each of the four food groups every day will give you a well-balanced diet. You should also eat the right amounts of these foods.
            Scientists have worked out a way of deciding how much food a person should eat. They have learned to measure the amount of energy different foods can provide. They have also studied people to find out how much energy is needed to do different things. From what they have learned, they have been able to figure out about how much food is needed by people of different types and people who do different things.
            When fats, carbohydrates, or proteins are chemically changes in your cells, kinetic energy is produced. Some of this kinetic energy makes it possible for your body to move. Much of it is produced as heat. Scientists have found a way to measure the amount of heat energy that a food can produce. For convenience, this measurement is used to represent all the potential energy of the food. The amount of energy that a food can provide is measured in a unit called the Calorie. One Calorie is the amount of heat needed to raise the temperature of 1 pound of water about 4⁰ F. The amount of energy that a food provides depends on the food. Fats produce more than twice as much energy as the same amount of carbohydrates or proteins.
            Scientists have studied different people and found that they need different amounts of energy. The amount of energy a person needs depends on such things as his age, size, and activities. The larger a person is, the more energy he usually needs. People who are very active need more energy than those who are not. The energy a person needs is also measured in Calories.
            Not all the food you eat is used immediately. Some of it is stored in your body for future use. Much of this food is changed into fat. A certain amount of fat is healthful. Whenever it is needed, it can provide your body with much energy. It also protects your skin, bones, muscles, and nerves from injury. Many people overeat and become too fat. Overeating makes the body digest more food than it needs. The extra food is changed into fat and stored. The weight of the extra fat puts an added strain on the heart and other parts of the body.
            The important thing for you to do is to form good eating habits. Here are some simple suggestions that will help your body make the best use of the foods you eat: 

1. Eat foods from the four food groups every day.
2. Eat three meals a day at regular hours.
3. Do not spoil your appetite with sweets.
4. Be willing to try new foods.
5. Do not rush through your meals.
6. Drink enough water and get plenty of fresh air, exercise, and sleep every day.