Resting Energy Expenditure (RER) refers to the amount of energy needed to maintain basic bodily functions such as breathing, circulation, and cell production while an individual is at rest. Accurately calculating RER can be vital for determining appropriate nutritional needs, understanding adaptations to exercise programs, and managing weight loss or gain. This article will explain how to calculate RER using a simple equation.

What is RER?

RER indicates the number of calories your body requires for its day-to-day functioning, even when you are not engaged in any physical activity. Your energy expenditure increases with increased physical activity, so understanding your RER provides a foundation for determining your total daily energy expenditure (TDEE).

Calculating RER:

There are several formulas available to estimate RER, but the Mifflin-St Jeor equation has been proven to be one of the most accurate methods and is very easy to use. The equation is as follows:

For men:

RER = 10 x weight (kg) + 6.25 x height (cm) – 5 x age (years) + 5

For women:

RER = 10 x weight (kg) + 6.25 x height (cm) – 5 x age (years) – 161

To calculate your RER using the Mifflin-St Jeor equation:

1. Convert your weight to kilograms if necessary by dividing your weight in pounds by 2.2.

2. Measure your height in centimeters if necessary by multiplying your height in inches by 2.54.

3. Plug in the numbers into the appropriate formula based on your gender.

4. Perform the calculations following the order of operations.

Example:

Let’s calculate RER for a 30-year-old woman who is 5 feet 6 inches tall (167.64 cm) and weighs 150 lbs (68.18 kg).

RER = 10 x weight (kg) + 6.25 x height (cm) – 5 x age (years) – 161

RER = 10 x 68.18 + 6.25 x 167.64 – 5 x 30 – 161

RER = 681.8 + 1047.75 – 150 – 161

RER = 1418.55

In this example, the woman has an RER of approximately 1418 calories per day.

Conclusion:

Calculating your RER is a crucial step in determining your overall energy needs and setting appropriate goals for weight loss, weight gain, or maintenance. By understanding your body’s baseline caloric needs, you can tailor your diet and exercise regimen to optimize your health and wellness.