The Macronutrients

Macronutrients come in three varieties: carbohydrates, proteins, and lipids. The body needs all three of these macronutrients to survive. To thrive, it needs them in the proper amounts. the following sections are a short course on macronutrients - what your body uses them for, where to find them, and how much you need of each.

CARBOHYDRATES

Carbohydrates come in three varieties: simple, complex, and fibrous. All three types contain about four calories per gram. Here's a breakdown:

• Complex carbohydrates, or starches, are found in legumes (dried peas and beans), grains, vegetables, and fruits.
• Fiber is found in whole grains, legumes, vegetables, and fruits.
  
• Simple carbohydrates, or sugars, are found in table sugar, honey, natural fruit sugars, and molasses.

Carbohydrates are the body's principal source of energy. They fuel all bodily functions, including the digestion of other foods. While the other macronutrients can also be converted into energy, carbohydrates are the easiest fuel source for the body to process.
According to the Food Pyramid, more than half of our daily calories should come in the form of carbohydrates. Here's how to get the most nutritional bang for your buck:

• Consume the majority of your carbohydrate calories in the form of whole grains, beans, potatoes, fruits, and vegetables.
  
• Minimize your intake of foods made with white flour and white sugar, such as cake, cookies, and candy.
  
• Eat high-fiber carbohydrates, such as bran cereal,apples, dry beans (kidneys, pintos, and limas), peas, parsnips, and potatoes.
  
  
  
  
  PROTEIN
  
  
  

Protein, like carbohydrates, contains four calories per gram. It performs two essential functions in the body: growth and maintenance of tissues, and formation of infection-fighting antibodies. Protein is found in many foods, primarily those of animal origin. High-protein foods include:

• Meat, Dairy Products, Poultry, Grain products, Fish and shellfish, Dry beans and peas,  Eggs
  

While it's important to eat enough protein (especially during childhood, adolescence, and pregnancy), too much protein can put unnecessary stress on the kidneys. It may also contribute to obesity, heart disease, and possibly certain cancers when the sources of protein consumed are primarily high-fat meat and dairy products.

The recommended dietary allowance (RDA) for protein is 0.8 gram per kilogram (2.2 pounds) of ideal body weight per day. Pregnant and breast-feeding women require an additional 30 and 20 grams, respectively.

LIPIDS

Lipids are a group of fatty substances that include fats, oils, and waxes. They help the body absorb and transport fat-soluble vitamins (A,D,E, and K), act as a ready source of energy, insulate against heat loss, and act as a cushion for many tissues and organs.
The following types of lipids are found in food: triglycerides, hydrogenated or partially hydrogenated fats and oils, cholesterol, and linoleic acid.

Triglycerides: the primary form of fat found in foods. Fat is composed primarily of three types of fatty acids: saturated, polyunsaturated, and monounsaturated. The biggest distinction between saturated and unsaturated fats is that the saturated ones, such as butter or shortening, are solid at room temperature. Vegetable oil (polyunsaturated) is not. Saturated fats are implicated in raising the body's cholesterol level and in clogging the arteries

Saturated fats are found in all animal products, as well as in coconut and palm oils. Polyunsaturated fats make up most of the fats in corn, safflower, sunflower, and soybean oils. Olive and canola oil contain mostly monounsaturated fat. Peanut oil has slightly more monounsaturated than polyunsaturated fat. In general, the less saturated fat an oil contains the more healthful it is.

Hydrogenated or partially hydrogenated fats and oils: lipids processed to prolong shelf life. They are semi solid at room temperature. Hydrogenating a fat or oil creates trans fatty acids, which research has found to be potentially more harmful than saturated fats.
Cholesterol: a white, crystalline substance found in all animal fats and oils.

Linoleic acid: the only "essential" polyunsaturated fatty acid. This means the body cannot synthesize this limit and must obtain it through dietary sources.

It's well known that one step in losing excess body fat is reducing fat intake. One reason is that fat contains nine calories per gram. (Remember, protein and carbohydrate have only four.) Also, the body needs to do minimal processing to store dietary fat as body fat; therefore, it processes and stores fat more readily than protein or carbohydrates. In addition to providing a hefty dose of calories, a high-fat diet is also associated with an increased risk of heart disease and certain types of cancer.

Most nutrition experts believe that no more than 30 percent of the calories you consume in a day should come from fat.