BMR, or basal metabolic rate, is a measure of how many calories a person burns with no activity. It is based on many factors, including age and gender. For a 28-year-old woman and 30-year-old man, average BMRs may be 1586.5 and 2108, respectively.
Due to their lower percentage of fat and higher percentage of muscle, men have higher BMRs on average than women. However, people who are leaner and more active have higher BMRs than people who are sedentary, regardless of sex. BMR increases with body weight for both males and females. BMR tends to decrease with age, slowing down approximately 2 percent every 10 years past the age of 20.