METABOLISM
The primary function of our metabolism is simply to provide the right amount of fuel (at the right time) to keep our bodies alive and functioning properly. It accomplishes this through a complex series of chemical reactions whereby food is converted to the energy we need. When we eat, the food we swallow enters our digestive tract and is broken down by digestive enzymes. Carbohydrates are converted to glucose, fats to fatty acids and protein to amino acids. Once these nutrients are broken down, they are absorbed by the bloodstream and carried into the cells of the body. Our metabolism then works to either release these nutrients as energy, use them to build and repair lean tissue or store them for later use.
There are two basic metabolic processes—one is constructive and is responsible for building and storing energy for the body. The other is destructive, though in a positive sense, as it breaks down nutrient molecules to release energy. The constructive metabolic process is called anabolism, while the destructive process is called catabolism.
Anabolism: promotes the growth of new cells, the maintenance and repair of tissues, and the storage of energy—usually through body fat—for future use. Small nutrient molecules are converted into larger molecules of protein, carbohydrates and fat.
Catabolism: is responsible for immediately providing the body energy to use. Instead of building up, it breaks down the nutrient molecules to release energy.
These two processes do not occur simultaneously but are balanced by the body based on several factors.
Catabolism, in particular—though some attribute this to overall metabolism—has three components:
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Basal metabolism: sometimes called resting metabolism, this is the metabolism component responsible for keeping you alive by ensuring normal body functions. Even if you were bedridden the whole day, basal metabolism is still at work. Basal metabolism is metabolism’s main component, as 60 to 70 percent of the calories from the food you eat are used for this. People who want to lose weight usually aim for a higher basal metabolic rate (BMR).
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Physical movement: this can range from a simple moving of your fingers to strenuous exercise. Usually 25 percent of the calories you consume are for this purpose.
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Thermic effect of food: this indicates the digestion and processing of the food you take in. Depending on the type of nutrient you consume, approximately 10% of the calories of the food you eat are burned through this. As you will see, the digestion of certain foods will require much more calorie expenditure than others. Protein takes a lot of calories to digest while carbohydrates take far less.
Thus, taking all this into account, here is our metabolism formula:
Calories From Food = Calories Expended From Basal Metabolism (60-70%) + Calories Expended By Physical Movement (25%) + Calories Expended Digesting Food (10%)
What Affects Metabolism?
Your metabolic rate, or how fast or slow your metabolism works, is influenced by a number of factors:
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Genetics: yes, metabolic rate is also inherited. Sometimes this makes an entire world of difference between a person who can eat almost everything and not gain an ounce and a person who easily balloons after indulging just once.
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Age: the younger you are, the faster your metabolism is. Metabolism slows down as you age. Women’s metabolic rate starts falling at the age of 30; for men, decline starts later at the age of 40.
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Gender: men have a faster metabolic rate—usually 10-15 percent faster—than women because their bodies have a larger muscle mass. Muscle plays a key role in a fast metabolism, as will be discussed in exercise portion of the 3 Week Diet.
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Amount of lean body mass: as already mentioned above, more muscle = faster metabolism.
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Diet: some foods will help you-some will only harm you. While timing is not everything, meal frequency greatly affects your metabolism.
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Stress level: stress is inversely proportional to metabolism. The more stress you are subjected to, the lower your metabolism will be.
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Hormones: specific hormones metabolize specific nutrients. How well the hormones work, then, directly affects metabolism. To a certain extent, diet and stress levels affect the hormones involved in metabolism, as you will find out later. Hormonal disorders or imbalances can affect metabolism as well.
Looking at all these factors that influence metabolism, you now probably have a general idea of what you need to do to increase your metabolism—accept the things you cannot change, and work on those that you can!
A “fast” metabolism is the true secret to maintaining a lean body.
