Whether your fitness goal is weight loss or muscle development, knowing your BMR (basal metabolic rate) is an important first step. Once you know your BMR, you will be able to create a personalized nutrition plan that adds or subtracts calories as needed to help you reach your goal.
BMR is basically the minimum amount of calories required to keep you alive in a resting state. You can think of it as the amount of food you would need to eat to run your body if you did nothing but sleep all day. Most people burn 70 percent of their daily calories just to breathe, pump blood around, and keep their body temperature up.
Your BMR will vary according many factors:
Now that you know all the factors influencing BMR, you'll understand why it can be so difficult to calculate!
The easiest formula for calculating BMR is simply to assume you need 35 calories for every kilo of body weight. However, obviously this formula is not very accurate, because it's only based on one factor! You're better off looking for a formula that makes use of multiple factors like gender, age, height and weight. For example, this is the Harris-Benedict Formula:
You can figure out your calorie needs based on your BMR by using an activity multiplier. If you get almost no exercise, multiply by 1.2. If you are moderately active, multiply by 1.55, and if you are training for marathon, multiply by 1.9.
The most precise BMR calculation will also take your lean body mass into account. In order to do this, you will need to get your lean body mass measured by a professional.