You've probably heard the word "metabolism" many times -- particularly if you're trying to lose or gain weight. Maybe you've heard someone described, or you've described yourself, as having a fast or slow metabolism. If you've ever noticed that some people seem able to eat more than others and not gain weight, you may have wondered if everyone's metabolism burns calories at the same rate. The specifics of metabolism can be complicated because metabolic rate is influenced by multiple factors.
Metabolism Basics
The terms "metabolism" or "metabolic rate" refer to your body's fuel efficiency, so to speak. Your metabolism is the rate at which your body uses energy -- or calories from food -- to power all your biological functions -- everything from breathing and digesting to playing tennis or running a mile. The University of Utah College of Health explains that your "resting metabolic rate," or RMR -- also called basal metabolic rate, or BMR -- is the rate at which your body burns calories when you're at rest, strictly to fuel biological functions like your heartbeat and respiration. But the other part of your metabolism is the rate at which your body burns calories to fuel your activities and exercise.
Influencing Factors
Metabolism is affected by several factors, some of which are within your control and some of which are not, and all of which vary from person to person. For example, genetics plays a large role in your metabolism, fully or partially determining such metabolism variables as gender, height and your body's levels of the hormones leptin and thyroxin, according to the College of the Canyons Health Services. Your age and growth spurts are additional uncontrollable factors that influence your metabolism. But other aspects of metabolism can be altered. Your amount of lean muscle mass and your level of physical activity help control your calorie-burning rate, and both these factors are modifiable.
Modifying Your Metabolism
According to the University of Illinois at Urbana-Champaign, basal metabolic rate is the biggest contributor to an individual's metabolism. The fact that one's BMR is highly genetically influenced helps explain why people do not all metabolize calories at the same rate. Even the potentially modifiable aspects of metabolism -- your amount of muscle mass and how much you exercise -- vary from person to person, which also explains differences between people's metabolisms. If you want to increase your metabolism, you can't change your genetics, but you can increase your muscle mass through regular strength training, as advised by the American Council on Exercise. You can also engage in more calorie-burning activity like vigorous cardiovascular exercise and moving more throughout the day. Both of these steps will speed up your metabolism both during your workouts and even while you're at rest.
Considerations
People burn calories at different rates -- some faster, some slower -- which is why you may not weigh the same as a friend who eats a similar diet and maintains a similar activity level as you do. If you have questions or concerns about your metabolism or would like to begin a new exercise program to influence your metabolism, check with your doctor first for safety and medical advice.
References
- University of Utah College of Health; Resting Metabolic Rate (RMR) Information
- College of the Canyons Health Services; Calories; Sheri Barke, M.P.H., R.D.; 2005
- University of Illinois at Urbana-Champaign McKinley Health Center; Breaking Down Your Metabolism
- American Council on Exercise; Strength Training 101
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