Wondering how many calories you need each day? That depends upon calories burned in a day!

A calorie is a measurement or unit of energy; calories in the foods you eat are a measure of the number of energy units that food supplies. Those energy units are then used by the body to fuel physical activity, as well as all metabolic processes, from maintaining your heartbeat and growing hair to healing a scraped knee and building muscle. Body weight comes down to a simple equation of calories in (from food) versus calories burned during exercise and other physical activity.

Use this calories needed per day formula to figure out how many calories you should consume:

STEP 1: Determine your RMR

RMR = 655 + (9.6 X your weight in kilograms)

+ (1.8 X your height in centimeters)

- (4.7 X your age in years)

Note: Your weight in kilograms = your weight in pounds divided by 2.2. Your height in centimeters = your height in inches multiplied by 2.54.

STEP 2: Factor in your daily calories burned during exercise

Multiply your RMR by the appropriate activity factor:

If you are sedentary (little or no activity): RMR X 1.2

If you are slightly active (light exercise/sports 1-3 days a week): RMR X 1.375

If you are moderately active (moderate exercise/sports 3-5 days a week): RMR X 1.55

If you are very active (strenuous exercise/sports 6-7 days a week): RMR X 1.725

If you are extra-active (very strenuous daily exercise, sports or physical job or training twice a day): RMR X 1.9

Calories Burned Result: Your final figure, based on calories burned in a day, represents the minimum number of calories needed per day to maintain your current weight.