Many of us often wonder how many calories we actually need to survive the day. The answer is simple, as all we need to do is calculate our Basal Metabolic Rate (BMR) and multiply the result by a factor that best represents our usual Physical Activity Level (PAL).

You have a choice of equations and online calculators to determine your personal BMR. One of the mathematical formulas is known as the “Harris Benedict equation,” and can be very useful in determining the number of calories you burn daily as your body attends to its simplest, automatic functions.

The Harris Benedict equation will estimate the amount of calories your body needs to keep functioning, just like the engine in your vehicle needs fuel to idle. The engine is running, but you’re not driving anywhere.

To stay alive your body needs a minimum amount of calories. In addition, it will need additional energy to power your daily physical activities. The more active you are the more energy you will need.  It is not much different from a car, which also need more fuel, the longer you drive it.

This means that if you are lying in bed all day, or spend it lounging in front of the TV, your body will require less energy than when you go for walks with your dog, or work out at the gym every day.

Knowing your BMR is important, especially if you want to lose weight. You need to know exactly how many calories you can eat a day to keep your weight afloat, and how many you have to deduct from that number, if you want to shed some kilos. Depending on your BMR, this could means, subtracting 500 calories a day if you want to lose 0.5kg over a week or 1000 calories a day, to lose 1 kilogram.

If that takes too long, you can speed up the weight loss and burn off more calories by increasing your physical activity level.

The Harris Benedict BMR Equation is:

-          Women= 655 + (9.6 x weight in kilos) + (1.8 x height in cm) - (4.7 x age in years)

-          Men= 66 + (13.7 x weight in kilos) + (5 x height in cm) - (6.8 x age in years)       

To estimate your total daily calorie needs you will have to determine your PAL. Choose a number that fits your activity level best from the list below, and multiply it with your BMR result.

-          1.2 = sedentary with little or no exercise

-          1.375 = light exercise, or sports 1-3 days/week

-          1.55 = moderately active with exercise, or sports 3-5 days/week

-          1.725 = very active with plenty of exercise, or sports 6-7 days a week

-          1.9 = extremely active with an intensive exercise regime, or sports twice a day

When putting together your weight loss plan, keep this equation in mind and use it in combination with other helpful weight loss tools, like food calorie calculators, meal planners, exercise calorie counters, progress trackers and more.