Daily Energy Requirements

Nutrition

Nutrition is the process of how the body takes in and utilizes food and other sources of nutrients.  It is a five part process that includes intake, digestion, absorption, metabolism, and elimination.

Daily Energy Requirements

The human body requires the nutrients in food for three major purposes:

To provide energy
To build, repair, and maintain body tissues
To regulate body processes

A person’s daily energy requirements depend on many factors.  To understand the relationship of food to good health, you need to understand how the body uses food.

Metabolism

Food must be broken down before the body can use it.  This process is an integral part of metabolism.  Metabolism is the sum of all the cellular processes that build, maintain, and supply energy  to living tissue.  During metabolism body tissue is built up and broken down, and heat and energy are produced.

Metabolism takes place in two phases.  In anabolism, substances such as nutrients are changed into more complex substances and used to build body tissues.  In catabolism, complex substances, including nutrients and body tissues are broken down into simpler substances and converted into energy.  The body uses the energy to maintain and repair itself.  Of the energy people get from the food they eat.  About 25% is directly used for bodily functions, and the rest becomes heat.

Each person’s body requires a minimal amount of nutrients to carry on a basic level of metabolism to live.  Each person’s daily nutritional requirements vary with age, weight, percentage of body fat, activity level, state of health, and other variables.  The body’s metabolic rate, or speed of metabolism, can also be affected by many factors, such as pregnancy, malnutrition, and disease.

Calories

The amount of energy a food produces in the body is measured in kilocalories.  A Kilocalorie, commonly called a calorie, is the amount of energy needed to raise the temperature of 1 kilogram of water by 1 C.  Foods differ in the number of calories they contain.  The more calories in a food, the more available energy it has.  Calories are also used to measure the energy the body uses during, all activities and metabolic processes.

As mentioned people’s daily nutritional needs differ, depending on variables of age, weight, percentage of body fat, activity level, and state of health.  If people eat an excess of calories - more than the body can use - the excess is stored as fat in the body.  Conversely, lowering caloric intake causes the body to burn off stored fat for energy.

Depending on the food’s weight (in grams) or volume, each food has a value in calories.  Therefore, you can count the number of calories a person consumes by monitoring, food intake and adding up the calories in each food serving.  You can use a food calories counte, such as those often found in cookbooks and in nutrition books, to look up caloric values.  A calorie counter tells you , for instance, that 1 cup of cooked carrots contains 50 calories or that 1 cup of cooked corn kernel contains 130 calories.  Calories are also listed on the labels of food packages.

You can estimate the number of calories a person burns during certain activities by consulting a chart similar to Table 49 -1.  You can se how many more calories a 190-pound person burns than a 120 pound person does during the same activity.

Table 49-1 Calories Burned per Hour in Selected Activities

Activity    120 -lb Person    190-lb Person
Bicycling     360    570
Football (touch)    288    456
Calisthenics    324    516
Handball    456    720
Hiking    300    480
Running (10 mph)    720    1140
Skiing (downhill)     426    672
Skiing (cross-country)    564    888
Soccer    456    720
Swimming    228    366
Tennis    330    522
Volleyball    258    408
Walking (2 mph)    156    252


Source:  Adapted from Marvin R. Levy et al., Life & Health:  Targeting Wellness (New York:  McGraw-Hill, 1992).



Chapter 49
Nutrition and Special Diets
Daily Energy Requirements

Medical Assisting
Administrative and Clinical Procedure
3rd Edition
Booth Whicker Wyman Pugh Thompson
McGraw Hill


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