The Importance of Burning Calories

Brian J. Sharkey and Steven E. Gaskill's Fitness & Health emphasizes the importance of regular, vigorous physical activity that burns calories.

Physical activity can be measured in terms of how many calories are consumed while doing it. When you exercise, your muscles burn fuel: sugars derived from food. They thus produce heat.

A "calorie" as commonly spoken of is actually, a kilocalorie, the amount of heat it takes to raise the temperature of 1 kilogram of water — equal to 1 liter — 1 degree centigrade. Hence, when your muscles work, the heat they give off is measured in kilocalories, or, in everyday parlance, calories. We accordingly speak of "burning calories."

In the section titled "Activity Reduces the Risk of Coronary Artery Disease" (p. 15ff.), Sharkey and Gaskill show how important calorie-burning exercise is to reducing the chances that you will ever have problems with coronary artery disease. CAD is "the nation's number-one killer for men and women," because it's what causes atherosclerosis and leads to burst blood vessels and blood clots in the heart." When that happens, you have a heart attack, a.k.a. myocardial infarct.

Scientific studies show, say Sharkey and Gaskill, that "the active life can slow, stop, or reverse atherosclerosis" (p. 17).

In one study (p. 18), Harvard alumni who burned 1,000 to 2,500 calories per week while exercising were only 71 percent as likely to die from coronary artery disease as those who burned less than 1,000 calories per week. The minimum level of activity to produce those results, 1,000 calories per week, is the equivalent of walking 30 minutes per day.

Those who burned more than 2,500 calories per week reduced their likelihood of CAD-related death to just 54 percent (!) of that of the less-than-1,000-calories control group. 2,500 calories per week is equivalent to 25 miles of jogging per week, since each mile of jogging uses up approximately 100 calories.