Calculating your Basal Metabolic Rate (BMR)


Walking, running and weight training use a considerable amount of extra calories during your workout, but your body also burns calories naturally when you are at rest. To figure out how many calories your body naturally burns each day, you can use a formula to derive an estimation. Then, adjust the number higher or lower based on variables including your body type, activity level and lifestyle, as well as any habits or special medical conditions you have.

Basal Metabolic Rate

The number of calories your body needs to maintain its basic physiological functions while at rest is your basal metabolic rate, or BMR. 

  • 60 to 70 percent of the energy your body uses is for this purpose
  • Another 5 to 10 percent helps you digest and metabolize food


People who naturally burn calories slowly often have difficulty maintaining a healthy weight.

Estimating Your BMR

You can estimate your BMR by plugging your age, weight in pounds and height in inches into the following formula: 

For women: 

  • 655 + (4.35 × weight (lbs)) + (4.7 × height (inches)) – (4.7 × age) = BMR 

For men: 

  • 66 + (6.23 × weight (lbs)) + (12.7 × height (inches)) – (6.8 × age) = BMR 


Although this can be a helpful guideline, other variables can make your BMR higher or lower.

Muscle Mass

A body with a greater ratio of muscle to fat requires more calories each day. Men, who are generally more muscular than women, burn more calories. Additionally, most people lose muscle mass as they age, so younger people tend to burn more calories than do older people. Weight training is an effective way to speed up your basal metabolism.

Genetics

According to Learn, culture and family practices play a role in determining a child's weight, but a slow or fast BMR is also partly hereditary. A child whose parents are not obese, she says, has only a 10 percent risk of becoming obese. With one obese parent, a child's risk of obesity goes up to 40 percent, and with both, 80 percent. This may be due to a genetic propensity for greater or lesser muscle mass or other outlying factors, but the fact remains that slow BMRs seem to run in families.

Demands to Your System

When your body must fight an illness or meet extra demands, it requires additional calories, so your BMR rises. People with a fever burn calories more quickly than people who are well, as do people who regularly engage in activities that stress the body, such as smoking cigarettes or drinking coffee. Breast-feeding and pregnancy, which both require your body to work harder in general, also cause you to use extra calories. In addition, people recovering from injuries or illness tend to burn more calories while at rest.

Activity

Weightlifting is not the only way to speed up your basal metabolism. Your heart, which is made of cardiac muscle, can also be strengthened by aerobic activity, making it better able to pump blood through your body and burn calories throughout the day. Active people tend to burn calories more quickly because of their lifestyles and because they are generally fitter, with hearts that are better able to pump blood throughout their bodies, burning extra calories all day long.