Category	Age	Calories per Day
		Light Activity	Moderate Activity	Heavy Activity
Children	4-6		1800
	7-10		2000
Males	11-14		2500
	15-18		3000
	19-24	2700	3000	3600
	25-50	3000	3200	4000
	51+		2300*
Females	11-18		2200
	19-24	2000	2100	2600
	25-50	2200	2300	2800
	51+		1900*
*Based on light to moderate activity   Pregnant women in their 2nd and 3rd trimesters should add 300 calories to the figure the table indicated for their age. Nursing mothers should add 500.

      Just what is a calorie, anyway? In strict physical terms, a calorie is simply a unit of measurement for energy. The body is a biochemical factory that is fueled by what we put in it and, like any other machine, it burns that fuel in order to perform its routine functions. The object is create a proper balance between caloric intake and the amount of energy the body requires for the tasks it is asked to perform.
      If that was such a simple feat, the frequency and degree of obesity we see around us would not be such a problem. Yes, there are other reasons why some individuals are over weight, but more on that in our Preventive Health section. This small chapter on nutrition deals specifically with eating.
      Naturally, the nutritive content of what we eat is very important, but so is the total volume of food, regardless of its dietary value. Too much of a good thing can be as bad for you as not enough. So just how many calories should you be consuming?
      The table above provides an estimate of the caloric requirements for the average individual. The figures are supplied by the U.S. Food & Drug Administration, and are derived from National Academy of Sciences' 1989 Recommended Daily Allowances. These numbers are intended to be approximations. Factors such as height, weight and body metabolism, for example, would affect the total number of calories required for each individual.