Several factors can influence an individual's basal metabolic rate (BMR), including age, gender, body composition, and hormonal levels. Generally, younger individuals have a higher BMR due to increased muscle mass, while BMR tends to decline with age as muscle mass decreases. Males often have a higher BMR than females because of higher muscle mass. Additionally, hormonal changes, such as those seen with thyroid function, can significantly affect metabolism. Understanding BMR can help tailor dietary and fitness strategies for weight management.