The primary determinant of basal metabolic rate (bmr) is the primary determinant of basal metabolic rate (bmr) is total daily calorie expenditure body mass index (bmi) lean body mass fatty body mass

I believe the primary determinant of basal metabolic rate is the Lean Body Mass. Basal metabolic is the rate of energy expenditure per unit time by animals at rest. It comprises the processes that the body requires to function. It is the amount of energy per unit time that a person need to keep the body operational at a state of rest.