Estimating Your Daily Calorie Needs
Energy or calorie needs vary from person to person and are based on a number of factors, including age, sex, height, weight, and activity level. The calorie levels are based on the Institute of Medicine’s estimated energy requirements (EER) and activity levels. They’re based on the calories needed to maintain energy balance in individuals who are at healthy body weights.
After you determine your daily calorie goals, you can determine a meal pattern that helps you meet your calorie and nutrient goals.
The following equation, called the Mifflin-St. Jeor equation, can also be used to estimate your resting metabolic rate (RMR); this can then be used along with an activity factor (a number based on how physically active you are) to estimate your daily calorie needs. The equation is based on weight, height, and age. Do the following:
• Convert your weight in pounds to kilograms. Because there are 2.2 pounds in 1 kilogram, divide your weight in pounds by 2.2; that will tell you how many kilograms you weigh.
• Convert your height in inches. Because 1 inch equals 2.54 centimeters, multiply your height in inches by 2.54; that will tell you how tall you are in centimeters.
• Determine your resting metabolic rate (RMR):
Women: RMR = 9.99 x weight (in kg) + 6.25 x height (in cm) – 4.92 x age – 161
Men: RMR = 9.99 x weight (in kg) + 6.25 x height (in cm) – 4.92 x age + 5
• Determine your daily physical activity level and multiply that by your RMR:
If sedentary, multiply RMR by 1.25.
If you have low activity (you walk at a pace of 3-4 miles per hour and walk the equivalent of about 1.5-2.9 miles per day), multiply RMR by 1.5.
If active (you walk at a pace of 3-4 miles per hour and walk the equivalent of about 5.3-9.9 miles per day), multiply RMR by 1.75.
If very active (you walk at a pace of about 3-4 miles per hour and walk the equivalent of 12.3-22.5 miles per day), multiply RMR by 2.2.
As an example, here’s how a 40-year-old female who is 5’3 tall, weighs 145 pounds, and walks about 2 miles per day, would figure out her daily calorie needs using the following equation:
• 145 pounds divided by 2.2 pounds per kilogram equals 5.9 kilograms.
• 5’3 equals 63 inches (there are 12 inches per foot); 63 inches multiplied by 2.54 centimeters equals 160 centimeters.
• 9.99 x 65.9 kg + 6.25 x 160 cm – 4.92 x 40 – 161 = 1301 (RMR).
• 1301 (RMR) x 1.5 = 1951 kilocalories
In this example, this woman would need approximately 1,951 calories to maintain her body weight.
Estimated energy requirement (EER) is the daily requirement for energy; it is calculated from a set of equations and factors that account for an individual’s energy intake, energy expenditure, age, sex, weight, height, and physical activity level.
Resting metabolic rate (RMR) is a clinical measurement of an individual’s resting energy expenditure; it is determined 3-4 hours after eating or performing significant physical activity and accounts for 60% – 75% of an individual’s total energy expenditure. Although RMR is often used interchangeably with basal metabolic rate (BMR), RMR is often slightly higher than BMR.