Macronutrients are the nutrients in the diet that are the key sources of energy, namely protein, carbohydrates and fat.
Water is essential for life. Two-thirds of our body weight consists of water. Water is part of every living cell. It is the medium for all metabolic changes (digestion, absorption and excretion). Water transports the nutrients throughout the body, acts as a lubricant and helps maintain our body temperature.
Calories are the amount of energy contained in food. Strictly speaking, one calorie is the amount of heat required to raise the temperature of one gram of water by one degree Celsius. Per gram, protein and carbohydrates supply 4 calories, fats and oils 9, alcohol 7. To maintain a healthy weight, the amount of calories being consumed shouldn't exceed the amount of calories being burnt off by physical activity.
Carbohydrates, also known as "carbs", are compounds of carbon, hydrogen and oxygen, which include starches, cellulose and sugars. They act as the primary biological means of storing or consuming energy. Other forms are fat and protein. Carbohydrates can be more easily converted into glucose than fat or protein and are therefore the body's "preferred" source of energy. There are two main classes of carbohydrates: simple carbs and complex carbs.
Simple carbs are sugars, like glucose, sucrose, fructose (fruit sugar) and lactose (milk sugar). With the exception of fructose (fruit sugar), simple carbs are basically sugars (glucose), so they are immediately absorbed into the bloodstream, causing a rise in blood-sugar levels. The body responds to this rise by secreting insulin from the pancreas into the digestive system. This will help disperse the blood sugar to other parts of the body. Usually the pancreas will secrete too much insulin, causing the blood sugar levels to drop too far. This will trigger hunger. The rapid rise and fall of our blood sugar levels is not healthy and can negatively affect our eating habits.
Simple carbohydrates can be found in: white and brown sugar, fruit sugar, corn syrup, molasses, honey, white flour, white bread, candy and alcohol.
Complex carbs are either starches or indigestible dietary fiber, like whole grains, beans and some vegetables. They need more time to be broken down into glucose, so they don't raise blood sugar levels as fast as simple carbs. That's why complex carbs are recommended over simple carbs.
Complex carbohydrates can be found in: starchy vegetables, whole grain breads and cereals, legumes, brown rice, quinoa, oats, bulgur, whole grain pasta.
Dietary fiber is a very complex carbohydrate. It has such a complicated chemical structure that the body cannot metabolize it at all. It is not broken down into glucose or other nutrients and passes through the body mostly undigested. Fiber is important for our health however, since it helps the body to process waste efficiently, it helps us to feel fuller for longer and it protects us against some serious diseases, including various cancers.
Please click here for some good food sources of dietary fiber.
A simple form of carbohydrate (see: Simple carbs).
Amino acids are the molecular building blocks of protein. There are about 23 amino acids. Of these 23, 9 are called essential or indispensable (IAA): histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. This means that they have to be supplied from some food or supplement source. The other amino acids are called nonessential or dispensable (DAA). These amino acids can be synthesized by the body from other amino acids.
Proteins are large molecules composed of one or more chains of amino acids. About 23 different amino acids are commonly found in proteins. The sequence of these amino acids will determine the specific shape and function of the protein. Proteins are required for the structure, function and regulation of the body's cells, tissues and organs. They are fundamental components of all living cells and necessary for the proper functioning of an organism. Each protein has unique functions. Examples are hormones, enzymes and antibodies.
To find an estimate of your personal protein needs, you can check out the Dietary Reference Intakes Macronutrients. A diet that contains a variety of grains, legumes and vegetables should easily provide all the protein our body needs.
Please click here for some good food sources of protein.
Fat is one of three nutrients used as energy sources by the body. The other ones are protein and carbohydrates. The energy produced by fats is 9 calories per gram. Protein and carbohydrates each provide 4 calories per gram. Fats that are in foods are combinations of monounsaturated, polyunsaturated and saturated fatty acids. Please click here for more information about fatty acids. The body needs only small amounts of fat. Excess intake of fat, especially saturated fat, can increase the risk of heart disease and stroke.
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