How Many Calories Should a Woman Have?

The use of calories to define a body's use of energy dates back to the 19th century, when the term calorie was coined to explain the creation of heat in the conversion of nutritional elements into energy through digestion. The current term that has replaced calorie is known as a joule. Both of these terms relate to the breakdown of carbohydrates, fats, proteins, organic acids and other elements into metabolic processes. Determining how many calories a woman should have daily depends on a wide variety of factors.

Determination of Caloric Intake Requirements

• According to the Mayo Clinic, the methods used to determine the minimum amount of calories required by women take into account the basal metabolic rate (BMR) and the amount of physical activity existing in each individual woman's daily life. BMR is the basic amount of food energy needed to maintain bodily function while at rest. Physical activity can include, but is not limited to, everyday functions, such as housework or gardening, and aerobic and other exercise regimens.

Physical Activity Factors

• There are several methods of calculating caloric intake and most of these reflect body weight in kilograms, which translates to 2.2 pounds. Determining physical activity levels is accomplished by calculating the amount of time spent in aerobic movement (not necessarily as an exercise regimen). Activity factor (AF) is quantified as light (20 to 30 minutes daily), moderate (45 to 60 minutes), heavy (75 to 90 minutes) and exceptional (up to two hours or more per day).

Activity Factor vs Body Weight

• According to Prevention Magazine, in most methods of calculating caloric requirements, the Activity Factor (AF) is multiplied using different ratios times body weight. In one such method, light AF uses a factor of 13 times body weight, moderate AF uses a factor of 16, heavy AF uses a factor of 19 and exceptional AF uses a factor of 22. Therefore, a woman who weighs 115 pounds and who gets between 75 to 90 minutes per day of aerobic activity should maintain approximately 2,185 calories of intake daily to provide the minimum amount needed.

Other Determining Factors

• Prevention Magazine also states that there are many other factors that will have an effect on a woman's caloric needs. While some of these are controllable, such as amount of body fat and daily exercise, other factors are not. These would include age, certain inherited genetic factors and physical conditions that alter calorie usage, such as pregnancy and illness. It is also generally understood that women require less calories than men due to how a woman's body burns calories.

Dieting and Calories in Women

• Although reducing caloric intake can result in weight loss, there is the potential for missing out on certain nutritional necessities when dieting. In general, the reduction of calories can have an immediate effect on the body other than weight loss and certain guidelines may be seen as precautionary to avoid the loss of essential nutritional values for metabolism. For example, reducing the daily caloric intake by 500 for one week can be seen as a safe place to begin so that no drastic changes are incurred on the body's overall metabolic health.