Most of the energy any person burns each day is meant just for keeping them alive; this is known as basal metabolism and can be calculated via the basal metabolic rate (BMR).
BMR and the Harris-Benedict Equation
The rate varies with age, sex, body weight and composition, and can be altered by a series of factors, such as dietary changes and weight lifting, push-ups and leg lifts; this type of exercise is called resistance training and can help you build your muscle mass and thus increase your basal metabolic rate.
You can determine your BMR easily by using one of the many calculators you can find online or use our BMR calculator that also uses Harris-Benedict formula. Note that there are two formulas, one for men, the other for women.
The Harris-Benedict Equation was created in 1919 and is one of the methods used for calculating a person’s basal metabolic rate, but adding in their physical activity levels. The result is important since it determines the total amount of energy (calories) you spend during a day, both while resting and when active.
Determining your Harris – Benedict Equation
Developed by scientists J. Arthur Harris and Francis G. Benedict, the equation takes into account the height, weight, age, and sex of the individual (the BMR part), as well as his or her activity levels.
You can see what your Harris – Benedict Equation is (in other words, how many calories you need per day to maintain your weight) by multiplying your BMR by your activity factor.
Therefore, sedentary people should multiply their BMR by 1.2, people practicing moderate exercise a maximum of 5 days per week should multiply their BMR by 1.55, whereas the formula for those who are active 6-7 days per week is BMR x 1.725. You can then use this information to adjust your daily calorie intake so that you can lose or gain weight.
The equation was improved in 1984, because while it is quite accurate, it leaves out lean body mass. What this means is that the Harris – Benedict Equation is less precise in the case of people who are very muscular or very overweight, given that muscular people need more calories while less lean people require fewer calories than shown by the equation.
Nonetheless, there are more accurate formulas used to determine BMR, such as the Mifflin-St. Jeor equation that was developed much later, in 1990, but the Harris – Benedict Equation still remains a useful prediction formula.