Did you know that you burn calories all day long, even if you’re just laying in bed? Your body is always using energy, whether you’re working up a sweat at the gym or laying around watching TV all day. It’s called your Basal Metabolic Rate (BMR), and it’s the estimated minimum level of energy required to sustain the body’s vital functions when at rest. In other words: it’s the number of calories you’d burn if you stayed in bed all day.
BMR varies person to person, taking into account age, weight, gender, activity level, and other factors. Here is a simple formula, not taking exercise or activity level into account:
MEN: 66 + (6.3 × body weight in pounds) + (12.9 × height in inches) − (6.8 × age in years)
WOMEN: 655 + (4.3 × weight in pounds) + (4.7 × height in inches) − (4.7 × age in years)
As you get older and lose lean muscle mass, your BMR is reduced, however, increasing muscle mass through strength training can increase it. Yo-yo dieting can also do a number on your BMR; Starvation or abrupt calorie-reduction can dramatically reduce BMR by up to 30 percent, and restrictive low-calorie weight loss diets may cause your BMR to drop as much as 20%.
But your basal metabolic rate accounts for only about 75 percent of your total daily caloric expenditure.
To determine your total daily calorie needs, multiply your BMR by the appropriate activity factor, as follows:
If you are sedentary (little or no exercise) : Calorie-Calculation = BMR x 1.2
If you are lightly active (light exercise/sports 1-3 days/week) : Calorie-Calculation = BMR x 1.375
If you are moderately active (moderate exercise/sports 3-5 days/week) : Calorie-Calculation = BMR x 1.55
If you are very active (hard exercise/sports 6-7 days a week) : Calorie-Calculation = BMR x 1.725
If you are extra active (very hard exercise/sports & physical job or 2x training) : Calorie-Calculation = BMR x 1.9
This is the total number of calories you need in order to maintain your current weight. Eat less calories to lose weight, more to gain, or stay right there to maintain! But remember never to drop too low below your caloric needs – that will only lower your BMR and hurt you in the long run. A good rule of thumb: aim for a net loss of 500 calories. Burn 250 through exercise, and cut 250 calories from your diet. That adds up to a one-pound loss per week!