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 Metabolism - What is it?

The Scientific Definition All chemical reactions within organisms that enable them to maintain life. It includes all physical and chemical processes within the body related to body functions. Processes of energy generation and use; including nutrition, digestion, absorption, elimination, respiration, circulation, and temperature regulation. The two main categories of metabolism are catabolism and anabolism. Catabolism is any metabolic process whereby cells break down complex substances into simpler, smaller ones, while Anabolism refers to any metabolic process whereby cells build complex substances from simpler, smaller units. Anabolic reactions usually require energy. The energy of catabolic reactions is used to drive anabolic reactions.

Metabolism - What is it?

Simpler Explanation of Metabolism

In very simple terms, your metabolism is the rate at which your individual body engine operates as it performs all it's bodily functions, like the creation/building of various substances (heat, muscle, proteins, RNA, hair, nails, enzymes, storage fat, bones) and the breaking down of others (food, storage fat, etc.). Both the creation/building process (anabolic, as above) and the breaking down process (catabolic) occur simultaneously, every moment. The fuel for all the chemical reactions which make up the metabolic process, is food.

Metabolism is Basically Genetic

Metabolism is basically a genetic inheritance and varies from person to person. You may have a faster metabolism than normal, for a person of your size, or a slower one. In this connection, the words "metabolism" and "metabolic rate" are often used interchangeably.

How Metabolism / Metabolic Rate Affects Weight

Your metabolism affects weight loss, weight gain and weight maintenance, because it determines how many calories you need. If you have a slower metabolism (you burn calories more slowly) your body needs fewer calories. So you may find it more difficult to maintain or lose weight on an average calorie-controlled weight loss diet. In such a case, you may have to increase your level of physical activity, as this is the only effective way to raise your metabolism/metabolic rate.

What Determines Overall Metabolic Rate

In simple terms, three factors contribute to your overall metabolic rate and thus the amount of energy (calories) you need to sustain your body weight.

1. Your Basal Metabolic Rate (BMR)

Sometimes referred to as Resting Metabolic Rate (RMR), BMR is basically the number of calories you burn at rest, when sleeping or simply sitting in a chair. This accounts for about 60 percent of all energy (calories) used by the body.

2. Your Additional Physical Activity

This accounts for about 30 percent of all energy (calories) used by the body.

3. Dietary Thermogenesis

Caused by the "thermic effect of food", dietary thermogenesis is the energy (calories) required to digest and process the food you eat. It accounts for about 10 percent of energy needs.


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