You likely know your metabolism is linked to your weight. But do you know how?
Common belief holds that a slim person’s metabolism is high and an overweight person’s metabolism is low. But this isn’t usually the case. Metabolism alone doesn’t determine your weight.
Rather, weight is dependent on the balance of calories consumed versus calories burned. Take in more calories than your body needs, and you gain weight. Take in less and you lose weight. Metabolism, then, is the engine that burns these calories and is the scale that regulates your energy needs.
Stated simply, metabolism is the process by which your body converts food into energy. During this biochemical process, calories — from carbohydrates, fats and proteins — are combined with oxygen to release the energy your body needs to function.
The number of calories your body burns each day is called your total energy expenditure. The following three factors make up your total energy expenditure:
- Basic needs. Even when your body is at rest, it requires energy for the basics, such as fuel for organs, breathing, circulating blood, adjusting hormone levels, plus growing and repairing cells. Calories expended to cover these basic functions are your basal metabolic rate. Typically, a person’s basal metabolic rate is the largest portion of energy use, representing two-thirds to three-quarters of the calories used each day. Energy needs for these basic functions stay fairly consistent and aren’t easily changed.
- Food processing. Digesting, absorbing, transporting and storing the food you consume also takes calories. This accounts for about 10 percent of the calories used each day. For the most part, your body’s energy requirement to process food stays relatively steady and isn’t easily changed.
- Physical activity. Physical activity — such as playing tennis, walking to the store, chasing after the dog and any other movement — accounts for the rema