Basal metabolic rate (BMR), also known as the resting metabolic rate, is the rate at which the body burns calories at rest. According to MayoClinic.com, the BMR represents 60 to 75 percent of your daily caloric expenditure. Some individuals blame a slow metabolism on their weight gain; however, a slow metabolism is rarely a factor, notes MayoClinic.com. A more thorough understanding of BMR can provide information that can contribute to successfully losing weight. Consult with a health care provider before beginning any weight loss regimen.
Background
The body is burning calories constantly to supply the energy necessary for various bodily functions. Energy is required for cellular repair and replacement, respiration and circulation, among others. The process of digestion, or thermogenesis, also burns calories. According to MayoClinic.com, thermogenesis accounts for approximately 10 percent of your daily caloric expenditure. Generally, it is best to measure BMR as soon as you wake up in the morning, when the body is completely at rest.
Factors
Many factors influence your BMR. Larger individuals have a higher BMR than smaller individuals. BMR also tends to decrease as we age, due to loss of lean body mass. Individuals with a high percentage of muscle mass will have a higher BMR than individuals of the same weight with less muscle. Muscle burns considerably more calories than fat. Men generally have a higher BMR than women of the same weight, because of greater lean body mass.
Activity
When beginning your weight loss regimen, the requirements of your diet and your BMR are going to be fixed for a period of time. Consequently, if your BMR is 1,500 calories a day, and your diet calls for 1,500 calories a day, daily activity will cause you to burn more calories than you are consuming. Ultimately, it is that daily calorie deficit that will result in weight loss. Increasing daily activity will increase the calorie deficit. A pound of fat contains 3,500 calories, so a calorie deficit of 3,500 is required to lose 1 lb. A regular exercise program can also increase your daily calorie expenditure. Consult with your health care provider, however, before starting any new exercise program.
Considerations
After several weeks of dieting and losing weight, your BMR may decrease. The reason for this change is that your overall body size has decreased, and your body requires less energy. Checking your BMR each 30 days can help you adjust your caloric intake and activity levels, to ensure that your weight loss is continuous. Your health care provider may be able to assist you in determining your BMR.
Misconceptions
A common misconception is that regular aerobic exercise will increase your BMR. A study conducted at Texas A&M University had 74 participants performing endurance exercise for 20 weeks. The results of the study showed no increase in their basal metabolic rates.
Warning
A very low calorie diet will continuously lower your BMR. The reason for the decrease is that the body slows down caloric expenditure to protect itself from starvation. Mammals have a similar metabolic slowdown during hibernation, where they go months with very little food.
References
- MayoClinic.com: Metabolism and Weight Loss: How You Burn Calories
- "The American Journal of Clinical Nutrition"; Alterations in Resting Metabolic Rate as a Consequence of 20 Weeks of Endurance Training; J.H. Wilmore, et al.; July 1998
- MayoClinic.com: I'd Like To Lose a Few Pounds. What's The Best Way To Boost My Metabolism?
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