CALCULATING YOUR DAILY CALORIC EXPENDITURES
Introduction
The Calorie is a unit of energy. Actually, the Calorie used to describe the energy
content of foods is sometimes known as the “big Calorie” because it is really equal to
1000 “little calories” (note how the “big Calorie” is capitalized, but the “little calorie” is
not). Thus sometimes we refer to the “big Calorie” as being equal to one kilocalorie
(abbreviated “kcal”; note the prefix “kilo” means “one thousand”). A “little calorie” is
enough energy to raise the temperature of one gram of water (one gram of water is
about one quarter of a teaspoon) by one degree centigrade or Celsius. Thus a “big
Calorie”, or one kcal, is enough energy to raise the temperature of 1000 grams of water
(= one liter or a little more than one quart) by one degree centigrade or Celsius.
From here on out, we will refer to the “big Calorie” merely as “Calorie.” But keep in
mind, some of your nutrition sources may refer to “kilocalories” or “kcal” instead of
“Calories.”
Calories are stored in the biological molecules that make up the food we eat. By
“burning” these biological molecules through cellular respiration we release this energy
for energy-requiring processes (e.g., normal metabolism and physical activity). When we
eat more Calories than we burn, then the excess Calories may be stored as biological
molecules (e.g., glycogen and/or fats) in our tissues and organs. Consequently, we gain
weight.
If we burn more Calories than we eat, stored biological molecules in our tissues and
organs must be used to meet these expenditures. As biological molecules are used
through cellular respiration this way, we begin to lose weight.
This situation means that acquiring and maintaining a healthy body weight is really just a
matter of balancing Caloric intakes with Caloric expenditures. You can calculate your
Caloric intakes by adding up the Caloric contents of the food you eat. To calculate your
Caloric expenditures, you need to calculate your resting metabolic rate (RMR) and the
energy consumed due to exercise, or your thermal effect of exercise (TEE). These
calculations are explained below.
Estimating Your Resting Metabolic Rate
Your resting metabolic rate (RMR) is the energy you expend while at rest (in Calories per
day). Its actual value depends upon a number of factors including age, sex, body
weight, and individual genetic factors. We will ignore the genetic factors and use a
simplified approach to estimating your RMR based upon your age, sex, and body weight.
The charts that follow present equations to use for calculating your daily RMR (in
Calories per day).
But first you need to know your body weight expressed in kilograms (kg). To do this
divide your weight in pounds (lbs) by 2.2. For example, a person weighing 154 lbs
Reference:
Your Guide to a Healthier Life 