Metabolism and weight loss:
How you burn calories
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. Metabolism: Converting food into energy
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.
Metabolism and your weight
It may seem logical to think that significant weight gain or being overweight is related to a low metabolism or possibly even a condition such as underactive thyroid gland (hypothyroidism). In reality, it's very uncommon for excess weight to be related to a low metabolism. And most people who are overweight don't have an underlying condition, such as hypothyroidism. However, a medical evaluation can determine whether a medical condition could be influencing your weight.
Weight gain is more likely due to an energy imbalance ? consuming more calories than your body burns. To lose weight, then, you need to create an energy deficit by eating fewer calories, increasing the number of calories you burn through physical activity, or preferably both.
If you and everyone else were physically and functionally identical, it would be easy to determine the standard energy needs. But many factors influence calorie requirements, including body size and composition, age, and sex.