Calories play an essential role in women's health, and yet can also lead to health problems. A calorie is a unit of energy. Like putting gas in the car, calories provide fuel for your body to fuction. However, eating too many calories leads to weight gain and associated health risks such as heart disease and diabetes. Good health requires that you balance your calorie intake with your energy output. Determining your recommended daily caloric intake depends on your age, height, weight and daily activity.
Recommended Caloric Intake
The American Heart Association recommends women aged 19 to 30 consume 2,000 to 2,400 calories a day depending on how active they are. Women who are 31 to 50 need fewer calories: 1,800 to 2,000 per day. However these numbers are general and don't take into account your body composition or goals. For example, if you are a 30-year-old woman who is sedentary and overweight, you may need to eat fewer calorie to lose weight. Or, if you are a 40-year-old woman training for a triathalon, you may need to consume more calories.
BMR
A more accurate way to determine your recommended caloric intake is to calculate your basal metabolic rate (BMR). Your BMR is the number of calories needed to fuel your body's basic functions. The BMR calculation for women is: BMR = 655 + ( 4.35 x weight in pounds ) + ( 4.7 x height in inches ) - ( 4.7 x age in years ). So if you are a 140 lbs., 5-foot 2-inch, 40-year-old woman, your BMR would be 655 + (4.35 x 140) + (4.7 x 62) - (4.7 x 40), or 1,367. The limitation to BMR is that it doesn't consider lean body mass or activity level.
Harris-Benedict Equation
In the early 20th century, Francis Benedict conducted studies on the basal metabolism that led to the creation of a formula for determining basal energy expenditure. Today, the equation is used to factor in activity level with BMR to more accurately calculate recommended calorie consumption. You can calculate your calorie needs by multiplying your BMR with the correlating activity factor:
Little to no activity: BMR x 1.2
Light Activity: 1-3 days a week: BMR x 1.375
Moderate Activity: 3 - 5 days a week: BMR x 1.55
Active: 6-7 days a week: BMR x 1.725
Very Active: Active lifestyle or job: BMR x 1.9.
A woman with a BMR of 1,367, who exercises three to five days a week, would have a recommended daily calorie intake of 2,119.
Weight Loss or Gain
Recommendations for calorie intake, including BMR and Harris-Benedict, provide numbers for weight maintenance. However, women who need to lose or gain weight need to adjust their calorie intake to meet their goal. Reducing calories and/or exercising more leads to weight loss. However, women need to be careful not to cut their calories too drastically. Not eating enough can slow down the metabolism and lead to health issues. Women who need to gain weight should add calories slowly, making healthy food choices to maintain proper health.
References
- Medline Plus: Diet - Calories
- American Heart Association: Know How Many Calories You Should Eat
- BMI Calculator: BMR Formula
- "Journal of the American Dietetic Association"; The Harris-Benedict Studies of Human Basal Metabolism: History and Limitations; DC Frankenfield, et al.; April 1998
- BMI Calculator: Harris Benedict Equation
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