Nutrition - Eating well: why it's important

Throughout history humans have written about food and its effect on the body. In recent years people have learned more and more about nutrition through laboratory studies conducted on animals and humans. The role of nutrition in health and disease has been recognized from research as early as 1900, although much remains to be learned.

Eating Well: Why It's Important: Words to Know

Body set-point theory:
The set point theory of weight control holds that the body will defend a certain weight regardless of external factors, such as calorie intake or exercise.
A mineral in the body that makes up much of the bones and teeth, helps nerve and muscle function, as well as the body's ability to convert food into energy.
A unit of energy contained in the food and liquids that people consume.
The body's primary energy source, carbohydrates are the body's fuel.
A cousin to fat, is a steroid found only in foods that come from animals, such as egg yolks, organ meats, and cheese.
Chronic disease:
An illness that is present for a long time. A frequently recurring disease, such as asthma.
Protein molecules that further chemical reactions in the body.
Part of every cell membrane and the most concentrated source of energy in one's diet, fat is used by the body to insulate, cushion, and support vital organs.
Stones made up of cholesterol or calcium that form in the gallbladder.
Heart disease:
When arteries become clogged with a fatty buildup; this can cause a heart attack or a stroke.
Substances found in the body's glands that control some of the body's functions, such as growth.
Iron-deficiency anemia:
When the body is lacking in the right amount of red blood cells, caused by a deficiency of iron.
Kidney stone:
Stones made of calcium or other minerals that form in the kidney or the ureter, which leads to the bladder.
The rate at which the body uses energy.
A nutrient that helps regulate cell function and provides structure for cells.
Food substances that nourish the body.
A condition marked by too much body fat.
A disease that causes bones to become fragile.
An organic substance made of amino acids that are necessary for human life.
Saturated fat:
Fat that is solid at room temperature.
Unsaturated fat:
Fat that is liquid at room temperature, like vegetable oil.
A strict vegetarian who doesn't eat any animal by-products or any dairy.
A person who lives on a diet free of meat products; some vegetarians will eat eggs or dairy products, while others will not.
A nutrient that enables the body to use fat, protein, and carbohydrates effectively.

By choosing healthy eating habits, people will gain many rewards. Eating healthy foods helps people maintain a healthy weight while also providing them with plenty of energy. Not only will people feel better and have more energy when eating well, but their skin, teeth, and hair will also reflect their good choices. The choices people make now can also affect their health later in life. People's risk for developing major health problems such as heart disease, stroke, diabetes, and cancer can be reduced if they make the right food choices a part of their lives. Good nutrition will help people to look and feel their best today and help prevent some of the deadliest health problems in the future. An unhealthy diet, lack of regular physical activity, smoking, and the over-consumption of alcohol are the leading contributors to premature death in the United States. It's important to eat well—good nutrition can save lives.

To better understand the diet link in health and disease, government agencies continue to study nutrition. Many controversies remain and a lot still needs to be explained; however, general guidelines have been developed to illustrate what Americans can do through proper diet to ensure good health.


Just as a car needs gasoline, a form of fuel, to run, people need food for fuel every day. Food is the source of all nutrients needed for life. Nutrients are substances used by the body for fuel, growth, and all body processes. The body needs more than fifty different nutrients every day to maintain proper health. Nutrient needs are higher in adolescence than any other time in the life cycle because the body is experiencing its biggest growth spurt at this time.

The nutrients people get from food are vitamins, minerals, carbohydrates, fats, protein, and water. People's bodies need all of these nutrients to remain healthy. Calories people eat come from fat, carbohydrates, and protein. Fat, carbohydrates, and protein are essential nutrients, which means people need them for good health. Vitamins and minerals are necessary for good health but have no calories. The body depends on good food choices to get all of these nutrients in the right amounts every day.

FAT. Fat provides the most concentrated source of energy in our diet. It also provides flavor and texture to foods. Fat in the body functions to insulate, cushion, and support vital organs and is a part of every cell membrane. Fat in our diet mainly comes from fatty meats, whole milk and whole milk dairy products (such as yogurt), butter, and baked goods. Fat can be saturated (solid at room temperature) or unsaturated (liquid at room temperature).

CARBOHYDRATES. Carbohydrates are the fuel the body needs to function. The brain primarily uses carbohydrates as its energy source. Most carbohydrates are plant-based from grains, fruits, and vegetables. There are three types of carbohydrates: sugar, starch, and fiber.

PROTEIN. Proteins act as the building blocks of the body. The body uses protein to make and maintain body tissue such as muscles and organs. It also functions as the key component of enzymes and hormones. Milk, eggs, cheese, meat, and fish are the most common sources of protein, although beans and nuts are good sources as well.

VITAMINS. Vitamins are needed in the right amounts by the body for normal growth, digestion, mental alertness, and resistance to infections. They enable the body to use fat, protein, and carbohydrates. There are thirteen different vitamins, four of which are stored in fat.

MINERALS. Like vitamins, minerals are needed in small amounts by the body. They help regulate cell function and provide structure for cells. There are fifteen minerals needed by the body; the most common ones are calcium, phosphorous, and magnesium.

WATER. Next to oxygen, water is most important to life. A person's body is 50 to 70 percent water. Although people can live for weeks without food, they can exist for only a few days without water. People need eight to ten cups of water each day.


Calories are units of energy contained in the foods people eat. The amount of calories a food has reflects how much energy it supplies to the body. The more calories a food has, the more energy it contains. The body needs energy to do everything from breathing and pumping blood to walking and running. If people eat more calories than their body burns, their body stores the excess energy as body fat.


The Dietary Guidelines for Americans take into account all of the currently known information about nutrition as well as the various controversies. These guidelines were issued jointly by the United States Department of Agriculture and the United States Department of Health and Human Services in 1995. The guidelines contain general health suggestions and dietary recommendations to help promote and maintain wellness.

These dietary guidelines give people direction in making better food choices to improve their health but they don't answer all of the questions of how to eat a more healthful diet. The Food Guide Pyramid was created to help better explain how to achieve the dietary guidelines.

Dietary Guidelines for Americans

Eat a variety of foods. It is important to eat a variety of foods from the different food groups each day. No two foods contain exactly the same nutrients in the same amounts. Varying the types of fruits, vegetables, grains, milk, or protein foods eaten each day helps people get all of the important nutrients their body requires.

Balance good nutrition with physical activity. Being an active person is just as important as eating healthful foods. Inactivity and poor nutrition are the leading risk factors associated with health problems later in life such as heart disease, high blood pressure, and diabetes. Being underweight can also pose serious health risks because it can mean the body isn't getting the essential nutrients it needs.

Choose a diet low in fat, saturated fat, and cholesterol. Eating a lot of foods high in saturated fat (fat that is solid at room temperature) can lead to the clogging of arteries, which can begin in the childhood years. When arteries become clogged with a fatty buildup, it is called heart disease. Heart disease can lead to a heart attack or stroke, two of the leading causes of premature death in the United States.

Choose a diet with plenty of grain products, vegetables, and fruits. Most grain foods, vegetables, and fruits are naturally low in fat and are packed with vitamins, minerals, and carbohydrates. Whole grain products, fruits, and vegetables also contain fiber, a nutrient important for good digestive health. A healthy diet is one that is based on these three food groups.

Choose a diet moderate in sugars. Filling up on sugary foods leaves less room for healthier foods with more vitamins and minerals. Foods high in sugar are often also high in fat and have been shown to cause tooth decay.

Choose a diet moderate in salt and sodium. Most people eat more salt than is needed. Excess salt in the diet has been shown to contribute to high blood pressure in people at a high risk for developing high blood pressure.

If you drink alcoholic beverages, do so in moderation. [Consumption of alcoholic beverages by minors is illegal and NOT recommended for children or teenagers under any circumstances.] Alcohol provides calories but few or no nutrients, can alter judgement, and can lead to a dependency or addiction. For adults, it is recommended that alcohol be consumed in moderate amounts.

Only the nutrients fat, protein, and carbohydrates contain calories and therefore provide energy. Vitamins and minerals don't actually supply calories but are vital in the processing of the energy-producing nutrients. Fat provides the most energy—nine calories per gram. Protein and carbohydrate both provide four calories per gram. A gram is roughly the same weight as a paper clip.

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