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The BMR calculator allows visitors to calculate how many calories they need on a daily basis. The calorie intake is calculated based on factors such as age, sex, height and weight, and activity level, i.e. sedentary, light or moderate activity, or very active or extremely active lifestyle.

Basal Metabolic Rate

The BMR is a measure of the amount of energy that people expend while at rest. In this state, the body uses energy only for the functioning of the brain, lungs, heart, liver, and other vital organs. Your body needs calories to perform different functions such as waste elimination, digestion, respiration, and heart beat. About 50 to 75 percent of the calorie intake goes toward your body's daily energy expenditure for essential functions. The rate increases when you build muscle mass and decreases with loss of mass. Age is another factor that leads to a lower BMR.

Using the Calculator

Using the calculator is as simple as plugging in numbers. For example, if you are a 38-year old female who weighs 115 pounds and is 5'4" tall and is moderately active, your basal metabolic rate is 1,277 which equals to a daily calorie consumption of 1,980 calories. If you have a sedentary lifestyle, you will need only 1,532 calories while if you are extremely active - your daily intake will be 2,427 calories. You will have the same basal metabolic rate.

Harris Benedict Method

The calculator uses the Harris Benedict Method, and the formula is different for women and men. For women, the equation is: 655 + (1.8 X height in cm) + (9.6 X weight in kg) - (4.7 x age in years). You can turn centimeters into inches and kilograms into pounds (1 kg is 2.2 pounds and 1 inch is 2.54 cm). A 31-year old woman who is 168 cm tall and weighs 49 kg needs 655 + (1.8 x 168) + (9.6 x 49) - (4.7 x 31) = 1310.2 calories. This is her basal metabolic rate. The next step is to account for your activity level. For example, if you have a sedentary lifestyle, you should multiply your BMR by 1.2 while if you are very active - by 1.725. For men, the formula is: 66 + (5 x height in cm) + (13.7 x weight in kg) - (6.8 x age in years).

Using the Calculator for Weight Control

The number you get by using the formula or calculator is the daily calorie intake to maintain your weight. You can do the opposite. Plug in your desired weight to check how many calories you need a day in order to lose weight. This will show you if you need to cut portion size and by how much. By the same token, if you are 5'6" and weigh 90 pounds, your daily calorie consumption should be 1665 calories. You can plug in your desired weight, say 115 pounds, and you need 1,814 calories a day if you are moderately active. So, you need to add 150 calories to your daily intake which is equal to the calories contained in two cups of popcorn or half a cup of oats with 1/3 cup of blueberries and a teaspoon of honey.

Factors to Take into Account

Your basal metabolic rate decreases when you gain weight. Building muscle mass speeds up your metabolism, but it is also determined by your genetic makeup. The best approach toward weight loss is to combine dieting with regular exercise. Exercise prevents muscle loss while following a diet helps lose weight.