Metabolism describes the collective, ongoing biochemistry of life. All metabolic processes either break down chemicals or build new ones. The building side of your metabolism is called anabolism; the breakdown side is catabolism. Both anabolism and catabolism occur continuously in your body and typically balance each other, although one or the other process may predominate at different times. An anabolic state of metabolism is one in which the building processes predominate.
Carbohydrate Anabolism
Your digestive system breaks down carbohydrates into simple sugars, which are absorbed into your bloodstream. When you ingest more sugar than your body needs to generate energy, carbohydrate anabolism kicks in. Your liver and muscles absorb the sugar glucose from your blood and transform it into a more complex storage form called glycogen. The pancreatic hormone insulin promotes this anabolic process known as glycogenesis. Diminished carbohydrate anabolism is one of the metabolic problems that occurs with diabetes mellitus. With this disorder, your pancreas does not produce enough insulin or your cells do not respond normally to the hormone. The resulting reduced level of carbohydrate anabolism contributes to an abnormally high blood sugar level.
Fat Anabolism
Conservation of energy is a metabolic survival mechanism and fat anabolism is your body's primary means of storing energy. The food you eat supplies fuel to generate the energy your body needs. Carbohydrates are your body's preferred fuel and fats are the backup. When you consume more carbohydrates and fats than your body needs to generate energy, fat anabolism occurs. Your liver packages excess dietary fats into lipoproteins, which function as transporters. Your fat cells, or adipocytes, absorb fat from lipoproteins and store it for future use. Excess dietary carbohydrates contribute to fat anabolism because your liver converts excess sugar into fats called triglycerides. Fat anabolism is the underlying metabolic process that leads to increased body fat when you overeat.
Protein Anabolism
Protein anabolism describes the formation of proteins from amino acid building blocks. Your body makes thousands of unique proteins, each of which performs a different function. The amino acids necessary for protein anabolism are either manufactured by your body or absorbed from your diet. When you suffer an injury, your body's normal rate of protein anabolism accelerates to replace the damaged tissue. Resistance training also prompts protein anabolism and helps you build lean muscle mass. Several hormones promote protein anabolism, including testosterone, growth hormone and insulin. Anabolic steroids are man-made chemicals that mimic the anabolic effects of testosterone. These drugs are used therapeutically to promote protein anabolism if you have muscle wasting due to disease. Illicit anabolic steroid use for athletic performance enhancement can lead to serious, potentially life-threatening health consequences.
Nutritional Effects
Your total caloric intake and the nutritional content of your diet influence the balance between anabolism and catabolism in your body. Eating a healthful diet with the recommended levels of nutrients help keep your protein, carbohydrate and fat metabolism balanced between anabolism and catabolism. In general, reduced dietary intake of a major nutrient promotes metabolic catabolism. Conversely, increased intake of a major nutrient promotes anabolism.
References
- "Nutrition"; Paul Insel, Ph.D., et al.; 2011
- "Exercise Biochemistry"; Vassilis Mougios, Ph.D.; 2006
- "Biochemistry"; Reginald H. Garrett, Ph.D., Charles M. Grisham, Ph.D.; 2010
- "Essentials of Strength Training and Conditioning"; Thomas R. Baechle, Ed.D., Roger W. Earle, M.A.; 2008
- Biology Cabinet; Metabolism; Nasif Nahle, B.S., M.S.; February 2007
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