The primary determinant of basal metabolic rate is an individual's fat body mass. gender. age. lean body mass.

The primary determinant of basal metabolic rate (BMR) is an individual's lean body mass. Lean body mass includes muscles, bones, organs, and other non-fat tissues, which are metabolically active and require more energy to maintain compared to fat tissue. Therefore, individuals with a higher proportion of lean body mass typically have a higher BMR.