Overview – Eating Well
The food you eat is the source of energy and nutrition for your body. Eating should be a pleasurable experience, not one that causes guilt or remorse. Getting enough food is rarely a problem, but getting enough good nutrition can be a challenge. What should you eat to stay healthy? Nearly everyone has an opinion, from your best friend to the daily newscaster. There is a lot of advice available, but the basics for good health have not changed since the first fad diets were introduced centuries ago.
Your body needs over 45 different nutrients every day. These nutrients are essential for health and must be provided in the foods eaten. These nutrients can be divided into five classes:
- Carbohydrates (starches, sugar, and fiber)
- Proteins (includes 22 amino acids)
- Fats (saturated, monosaturated, and polyunsaturated fatty acids)
These nutrients work together and interact with body chemicals to perform several functions.
- Provide materials to build, repair and maintain body tissues
- Supply substances that function in the regulation of body processes
- Furnish fuel for energy needed by the body
Each nutrient has a certain special job to do in the building, maintenance, and operation of your body. Some jobs require that nutrients work together as a team. These jobs are nutrient-specific. They cannot be done by other nutrients—an extra supply of one nutrient cannot make up for a shortage of another. That’s why a balanced diet including all food groups is so necessary. Your body needs all of these nutrients, not just a few. Some nutrients need to be replenished every day from food, while others can be stored in the body for future use.
The Energy Providing Nutrients
Of the six classes of nutrients, only 3 provide energy: Carbohydrates, Fats and Proteins. Energy is the body’s most basic need. Energy is used when you breathe, when the heart pumps blood, and when you sit, stand and walk. The more vigorous the activity, the more energy is required.
The energy contained in a carbohydrate, fat or protein is measured in kilocalories, commonly shortened to “calories” in the United States. The calorie is a measure of energy available to the body. When you eat something, the number of calories it contains is the number of energy units it provides to the body for its needs. The calorie is also a measure of energy your body uses in everyday life or exercise.
Where the Numbers Come From
A bomb calorimeter is a special instrument used to measure calories in food. The food is first dried to remove water and then placed in a special container that rests in water. When the food is burned, heat is transferred to the water. The amount the burning food heats the water is the measure of calories. One calorie is the energy needed to raise the temperature of 1 gram of water 1 degree centigrade.
The energy values of the 3 calorie-providing nutrients are as follows:
1 gram of carbohydrate = 4 calories
1 gram of protein = 4 calories
1 gram of fat = 9 calories
Calories may also be added to food intake by consuming alcoholic beverages. Alcohol is not a nutrient because it cannot be used in the body to promote growth, maintenance, or repair. It is a toxin that is broken down as an energy (calorie) source and can be converted to fat.
1 gram of alcohol = 7 calories
Nearly all foods supply energy or calories. However, some provide more calories than others. No single food or kind of food is “fattening” by itself. When the energy provided in food is not used – whatever food it is – the excess is stored in the body in the form of fat. Storage of too many excess calories results in being overweight.