Energy balance refers to the relationship between the units of energy, or calories, consumed in food and the units of energy used by the body to move and to maintain its systems. You can achieve a healthy energy balance by making sure that your body uses most of the energy it consumes. To do that, you may need to calculate energy intake vs energy output.
Calculating your energy intake is simple. You record and add up the calories in everything you eat or drink. Calculating your energy output is a little more complicated. Energy output consists of the three components described on the tabs below.
Basal Metabolism
Physical Activity
Thermic Effect
of Food
Basal metabolism refers to all the chemical changes that take place in your body’s cells. Building and repairing tissues, circulating and filtering blood, and releasing heat to maintain body temperature are all functions of your metabolism. The largest portion of your daily calorie use (50%-70%) goes to fuel these cellular activities.
A person’s metabolic rate, the rate at which their body uses energy, depends on their age, sex, thyroid function, and muscle mass.
Most people think about physical activity when they think about expending energy, or burning calories. How much energy is expended depends on the type of activity, its intensity, and its duration (how long it lasts). For most of us, the total number of calories expended daily for physical activity is less than the number expended for basal metabolism. Together, basal metabolism and physical activity account for about 90% of a person’s energy expenditure.
The thermic effect of food refers to the amount of energy required to digest, absorb, and process the nutrients from food. This component of energy expenditure is small, less than 10% of the energy you expend daily.
Once you know the factors involved in energy balance, how can you use that knowledge to get and stay healthy? Basically, you need to remember these three rules.
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When calorie intake equals calories expended, you maintain weight. |
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When calorie intake is less than calories expended, you lose weight because your body burns stored fat for energy. |
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When calorie intake is more than calories expended, you gain weight because your body stores many of the excess calories as fat. |
