How To Figure Out How Many Calories I Should Consume

Knowing your body's daily calorie needs can help you maintain a healthy weight. Optimal energy requirements vary throughout your life cycle and during various physiological conditions. You need additional energy and types of food when you have certain diseases, when your body is healing from a major surgery or injury, when you are under stress and when you are pregnant or lactating. The more physically active you are, the more energy you need.

Scientists have the ability to accurately measure total energy expenditure in individuals but, because of the expensive and intrusive laboratory techniques, clinicians still rely primarily on prediction equations. Several mathematical formulas are available to estimate average energy requirements.

Step 1

Weigh yourself to the nearest pound on the bathroom scales.

Step 2

Divide your weight in pounds by 2.2 on the calculator to get your weight in kilograms.

Step 3

Determine your calories per kilogram factor based on your age and gender. From ages 19 to 24, females need 38 calories per kilogram and males need 40 calories per kilogram. From ages 25 to 50, females need 36 calories per kilogram and males need 37 calories per kilogram. Over age 50, both females and males need 30 calories per kilogram, according to Kathleen Mahan and Sylvia Escott-Stump in "Krause's Food, Nutrition, & Diet Therapy."

Step 4

Multiply your weight in kilograms by your calories per kilogram factor to get your total calories required.

Step 5

Adjust the total calories required if you have a goal to gain or lose weight. Add 500 calories per day to total calories to gain 1 lb. per week or add 1,000 calories per day to gain 2 lbs. per week. Subtract 500 calories per day from total calories to lose 1 lb. per week or subtract 1,000 calories per day to lose 2 lbs. per week, according to MayoClinic.com. One pound is roughly equivalent to 3,500 calories, so adjusting your intake up or down by 500 calories per day is the equivalent of 3,500 calories or 1 lb. per week.

Tips and Warnings

This calculation produces an average daily energy allowance in calories, based on your age and weight. To meet your individual needs, a registered dietitian will estimate your resting metabolic rate using a mathematical formula such as the Harris-Benedict formula and the energy you expend in physical activity based on your lifestyle and level of activity. Your personalized calorie requirement also includes consideration of any disease state, injury or special nutritional or metabolic needs you may have and conditions such as pregnancy and lactation.
Weight-loss diets need to promote optimal nutritional status based on individual needs. For health, women should not consume fewer than 1,200 calories per day. Men should not consume fewer than 1,500 calories per day.