It is in every cell in your body. It refers&nbsp;to a series of chemical processes in each cell that turn the calories you eat into fuel to keep you alive.The body's major organs — the brain, liver, kidneys, and heart — account for about half of the energy burned at rest, while fat, the digestive system, and especially the body's muscles account for the rest.

Your metabolism

Health

There are 3 main ways:<ul><li>the basal metabolism, the&nbsp;energy used for your body's basic functioning while at rest</li><li>the energy used to break down food (also known as the thermic effect of food)</li><li>the energy used in physical activity.</li></ul>Most of the energy you burn is from your resting metabolism.

How we burn energy

Metabolism can vary a lot between people, and researchers don't understand why.2 people with the same size and body composition can have different metabolic rates. One can consume a huge meal and gain no weight, while the other has to carefully count calories to not gain weight.

Metabolism variations

Getting older slows down the metabolism.The effect happens gradually, even if you have the same amount of fat and muscle tissue. So when you're 60, you burn fewer calories at rest than when you're 20.

Metabolism and getting older

There's a lot of hype around" speeding up your metabolism for weight loss, but that's just a myth.While there are certain foods (coffee, chili, and other spices) that may speed the basal metabolic rate up just a little, the change is so negligible and short-lived, it would never have an impact on your waistline.&nbsp;Building more muscles, however, can be more helpful.

You can't speed  your metabolism

Drastic dieting can slow down your metabolism.&nbsp;This may be the body's way of vigorously defending a certain weight range, called the set point.Researchers don't fully understand why this metabolic slowdown happens though.

Diets and metabolism

We talk about metabolism like it's something we can manipulate by gulping a pill, downing some green tea, or running faster. You've seen the articles headlined "Boost your metabolism" or "Try this high-metabolism diet to lose weight." But this obscures many truths about this essential, yet still somewhat mysterious, biological process.

Your metabolism

Metabolism: Myths and facts

Anabolism

Catabolism

Body Weight

10 Easy Ways to Boost Your Metabolism (Backed by Science)

Eat Plenty of Protein at Every Meal

Drink More Cold Water

Do a High-Intensity Workout