Genetics

• Much like the color of your hair or how tall you are, basal metabolism is partially determined by your genetics. In this way, some people are simply born with faster metabolisms than others.
  
  

Gender

• Men have higher basal metabolic rates because they have a greater muscle proportion of muscle mass and a lower body fat percentage than females; more calories are required to maintain muscle than fat.
  
  

Age

• Basal metabolism decreases as we age. It is said that after 20 years of age, it drops about 2 percent per decade.
  
  

Exercise

• Physical exercise, both aerobically and anaerobically, will also help to raise your BMR by enhancing or building extra lean tissue. In this way, you will burn more calories even when sleeping.
  
  

Body Surface Area

• Basal metabolic rate is also a reflection of height and weight. Much like weight, the greater surface area of your body, the higher your BMR will be.
  
  

Diet

• Starvation or crash diets can dramatically reduce BMR because your body adjusts to caloric deficiencies to compensate.