Understanding metabolism is difficult because it is highly personal. There are formulas and ways to guess what your metabolic rate may be, but unless you actually get a metabolic test done, the estimations may be inaccurate. Too many calories results in weight gain, but too few can slow metabolism and hinder weight loss as well. Knowing your metabolic rate will aid in weight loss, as it will help you figure out how many calories you need to consume to maintain daily energy needs without going overboard.
According to Medline Plus, metabolism refers to all the physical and chemical processes in the body that convert or use energy. Food is so much more than the delicious things you eat; it is the fuel that keeps the body working. All body processes require energy, from digestion, to pumping the heart, to breathing. If too much food is consumed and your metabolism cannot convert it all to energy, then it gets stored as fat. If you consume less than your body needs, it relies on fat stores to make up the rest of the energy requirements.
Basal metabolic rate, or BMR, is the minimum number of calories your body needs to function in a completely rested state. That is a baseline measurement, because when you add walking, moving and activities of daily living, that caloric requirement increases. To calculate a simple estimate of what your BMR is, multiply your weight in pounds by 10 if you are female and by 11 if you are male.
The basic metabolic test will estimate your BMR and even add in estimations for working out and activities of daily living. According to Northwestern Memorial Hospital, the test usually involves breathing into a tube for about 10 minutes. The test calculates the amount of oxygen inhaled to the amount of carbon dioxide exhaled. The more oxygen your body uses, the higher your BMR. It will generally tell you if you fall within BMR norms for your age and gender. If your metabolism falls below average, there are ways to increase it to facilitate weight loss.
There are many factors that influence how fast your metabolism is. It is a misconception that the more fat you have, the slower your metabolism is. In reality, the more mass you have, the more energy is required to maintain it, so generally heavier people have slightly higher BMR than thinner people. However, muscle burns far more calories at rest than fat, so athletes will generally have higher metabolisms than others. Age and gender also influence metabolism. Generally, as you age, metabolism decreases.
A common belief is that by cutting calories drastically, you will lose weight. However, your body needs food to convert to energy. Without adequate food, energy levels go down, so metabolism decreases. You may lose weight at first, but it is prone to coming right back when a normal amount of food is consumed, because your metabolism sank so low. A better option is to eat small meals throughout the day so your body is constantly fueled and metabolism is constantly working to create energy. Have a metabolic test to determine your BMR and try to consume at least that amount of calories daily; that way you will still be in a deficit when you factor in daily lifestyle activities.
- Medline Plus: Metabolism
- “Essentials of Strength Training and Conditioning”; Thomas R. Baechel, Roger W. Earle; 2008
- "Advanced Health and Fitness Specialist Manual”; American Council on Exercise; 2009