We use energy all the time, whether we are running, eating or sleeping. The energy we use at rest – to pump blood, digest food, regulate temperature, repair cells, breathe or think – is our basic metabolism, which is minimal energy. necessary to maintain the basic biological functions of the body. So if we carry extra weight, it is because we are taking in more energy than we are using. (Cursed much thickening around our belly is a combination of accumulated deep visceral fat and shallower subcutaneous fat.)
When we expend energy during bursts of intense exercise and other physical activity, the glycogen in our muscles is used first. The liver secretes glycogen to help muscles function and regulate blood sugar. After about 30 to 60 minutes of aerobic exerciseThe body begins to burn fat.
If we take in less energy than our overall body needs to sustain – like when dieting – the body often turns to stored fat for energy. When your body metabolizes fat, Fatty acid molecules are released into the bloodstream and travel to the heart, lungs and muscles, where they break them down and use the energy stored in their chemical bonds. The weight you lose is essentially a byproduct of that process. They are excreted in the form of water – when you sweat and pee – and carbon dioxide, when you exhale. In fact, the lungs are the main fat excretory organs.
The body uses energy to perform its normal basic processes at rest—again, your basal metabolism—and for the physical activity you perform on it, which is considered your active metabolism.
