If you use the dotFIT program as designed by entering all your personal statistics (height, weight, age, gender etc.), the program uses the evidence-based Mifflin St. Jeor formula to calculate your basal metabolic rated (BMR) and adds that to the activity level you picked from the questionnaire that best describes your current lifestyle to estimate your average daily burn. If you use an activity monitoring device such as Fit-Bit, you can plug it into the program and use it to deliver your calorie burn instead of the native formula. Each week (or biweekly if using body fat) you enter your personal statistics and they are changed, the program recalculates your calorie burn to match the physical changes (e.g. less body weight/fat).