What is Metabolism ?

Metabolism is the rate at which your body burns calories in order to maintain itself. Whether you are walking, eating, drinking, sleeping etc. your body is constantly burning calories . Even while we sleep our metabolism is working. Metabolism is a constant process that begins when we're conceived and ends when we die. It is an important process for all life forms. If it stops, a living thing dies.
Total Daily Energy Expenditure or Metabolic Rate Graph

The body burns calories in three ways : Basal Metabolic Rate (BMR) , physical activity , and the thermic effect of food.

Basal Metabolic Rate (BMR)	This is a measure of the energy that your body uses when it is inactive. It represents the minimum amount of energy required to keep your body functioning, including your heart beating, lungs breathing, brain working and body temperature normal. BMR accounts for 60-75% of daily calories burned. This means you burn the most calories while at rest. The faster your metabolic rate the more calories you burn. The number of calories required for basal metabolism varies with sex, age, body size, lean muscle mass and hormones. People with a high percentage of muscle mass burn more calories while at rest. This means it is important to not only lose fat but to gain muscle in the weight loss process. By increasing your total muscle mass, you can increase your metabolic rate which helps in weight loss.
Physical activity	It accounts for around 20% of calorie expenditure .You can determine the amount of calories you burn according to your workout and intensity. Also, you can control the number of calories burned depending on the duration, frequency and intensity of your physical activities.
Thermic Effect of Food	It accounts for about 10% of the total energy used by an average person. It is the energy used by our body when we eat and digest food so that it can be metabolised by the body. In other words our body needs energy to breakdown and process the food.