Being able to determine your basic metabolic rate (i.e., the amount of energy or calories your body burns to maintain itself in its resting state), would not be easy, or an option most people have available to them. Two methods exist -- direct calorimetry and indirect calorimetry. The direct method involves placing a person in an insulated chamber. As the person's body heat is released, it raises a layer of water surrounding the chamber, and this allows scientists to measure temperature. Remember, a kilocalorie is the amount of heat it takes to raise the temperature of one liter of water by 1 degree Celsius. In this manner, scientists can calculate the number of calories a person expends.

The other method, indirect calorimetry, measures the amount of oxygen a person uses. There is a relationship between the body's use of oxygen and the energy it expends, so scientists use formulas to convert gas usage into energy/calories used.

A rough estimate to use in trying to determine your minimum caloric or energy needs is 9 calories/pound, if you are a sedentary person, and decreasing this by 100 calories for every 10 years of age over 30. But, it is unlikely that you are a total couch potato; so, if you get some physical activity every day, such as light walking, increase your need to 13 calories/pound; for heavier activity, to 20 calories/pound. The same rule applies for increasing age, however, and decreasing calories.

There are other factors besides age that will have an affect on the above "rough" estimates of how many calories you need. Remember, the more muscle you have in relation to fat, the more calories you will burn. Metabolism can also be affected by thyroid and other hormone levels.

What's important is that you eat enough food to maintain your body processes and have caloric energy to get not only your work accomplished, but feel good enough to play....(or vice-versa) everyday. Without enough calories, the body will resort to burning its own muscle for fuel -- a condition that will leave a person thin, but fatter.

If you determine, through your calculation, that the number of calories you need doesn't appear to be many, say 1200 - 1500, make sure you don't waste them on junk food. It's even more important for you to think "nutrient dense" and go for foods that are complex carbohydrates (starches) and fresh fruits and vegetables, as well as dairy products and protein sources that are lower in fat. This type of balanced, nutrient dense diet should give your body the vitamins and minerals it requires and the energy it needs.

If you have other dietary questions, don't hesitate to make an appointment with the Registered Dietitians at the University Health Service. Call x4-2284, and press #2,...and then walk briskly to your appointment!

Alice

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