Why You Should Know Your Basal Metabolic Rate

We all need energy to keep our bodies going and to fulfill our daily obligations, no matter what they may be. We obtain that energy from the food and drink we consume – but if you eat more than you need, you gain weight.

The key to achieving and maintaining a healthy weight is to know exactly how much food and drink you need – and then to stick with that amount.

If your body stayed asleep for 24 hours, the amount of energy your body would burn just to sustain itself through those well-rested 24 hours is your resting metabolic rate – also known as your basal metabolic rate, or BMR. The BMR is important when beginning a weight loss plan, because from this number you can calculate how much you can eat in order to achieve your weight loss goal.

Your BMR depends on several variables. One of the most important factors is body composition. When a person has a greater ratio of lean body tissue (muscle) to fat tissue (body fat) the higher the BMR will be. A key element to any fitness program should be increasing lean muscle through resistance training and decreasing fat tissue by way of cardio training (i.e. walking, jogging, climbing, etc.). Age, height, growth stages, and environmental factors can all increase the BMR. Fasting and malnutrition will also lower your metabolism.

BMR can be estimated with a calculation, but that doesn’t take into account your unique metabolic rate since the equation doesn’t know your fat-to-muscle ratio. The most accurate way to know your BMR is to get a BMR test. It’s a simple, non-invasive test; you’ll lie comfortably in a chair and breathe into a small mouthpiece and tube connected to the BMR machine for about 10 minutes. At the end of the test, the machine calculates your results.

Here’s how knowing your BMR can help your weight loss goals: Let’s say your BMR number is 1600 kcals (kilocalories) per day. That means that your body needs 1600 kcals for its basic life-supporting functions – it does not include the calories that you use for regular day-to-day activities (e.g. when you drive your car, work at the office, run errands, or play racquetball). Thus, if your goal is to lose weight, limiting your daily caloric intake to just 1600 calories per day means that, while you are performing your regular day-to-day activities, your body will be using calories from your body’s fat stores. If you add regular exercise on top of those regular day-to-day activities, you’ll reach your weight loss goals faster.

With the knowledge of your BMR, weight loss can really be a simple equation of addition and subtraction.

Side note: The BMR is different from the BMI, or Body Mass Index. The BMI, which classifies people as "underweight," "normal weight," "overweight" or "obese," is calculated by simply dividing a person's weight by their height squared. This BMI system of classifying body weight has come under recent attack as being inaccurate, since it does not take into account body composition – i.e. whether or not excess weight is due to fat versus muscle.