Factors that can influence an individual's basal metabolic rate (BMR) include age, gender, body composition, and genetics. As individuals age, BMR tends to decrease due to the loss of lean muscle mass. Men typically have a higher BMR than women due to greater muscle mass. Additionally, having more muscle relative to fat increases BMR, as muscle tissue requires more energy to maintain. Environmental factors such as temperature and hormonal balance also play a role in determining BMR, impacting overall energy expenditure.