Anabolic and catabolic processes

Our body needs to break down the nutrients we get from the food into simple molecules which then can be used for the production of ATP (adenosine triphosphate, the main energy molecule which the cells can use to carry out cellular processes) and other biological molecules (such as proteins, fats, etc. The overall process which includes the breakdown of nutrients into smaller molecules and the building up of bigger molecules from smaller ones is called metabolism.

Many people, when thinking about metabolism, think about losing weight and building muscle but the metabolic processes are important for every cell in our body because they provide energy for the cells. Metabolism, on other hand, includes anabolism and catabolism. Those are types of biochemical reactions and the anabolic processes make complex molecules using simple ones, while the catabolic processes break down larger molecules into smaller ones.

What are the main things to remember

Anabolic and catabolic reactions are broad types of reactions which, taken together, make up the metabolism.
Anabolism consists of making up complex molecules using simple ones and those processes use up energy. The hormones which are involved are estrogen, testosterone, growth hormone, insulin. The anabolic exercises are usually anaerobic and build muscle mass. Some example of
anabolic reactions are when the amino acids are assembled into proteins.

Catabolism consists of breaking down complex molecules into simple ones and those reactions lead to release of energy. The hormones which are involved are cortisol, adrenaline, cytokines and glucagon. The catabolic exercises are typically aerobic in nature and are helpful for burning up calories and excess fat. An example for catabolic reaction is when proteins are broken down to amino acids.

Usually both types of reactions work together and the energy gained from the catabolic reactions provide energy for the needs of the anabolic reactions.


Anabolism is also called biosynthesis because its processes build up complex molecules using simple ones. Those types of reactions require energy to be used and don’t occur spontaneously.
Usually the necessary energy is provided by the catabolic reactions. The ATP (adenosine triphosphate) should be hydrolyzed which leads to the breakdown of one of its phosphate bonds. This bond stores energy and, when broken down, releases it so the cell can use it. Other
mechanisms behind those processes are the reactions of condensation and reduction.

Anabolic reactions are used to grow tissues, make up polymers and repair damage. Some examples of such processes are when glycerol and fatty acids make up lipids, when, during photosynthesis, water and carbon dioxide make oxygen and glucose, etc.

Anabolic hormones

  • Testosterone – most people relate testosterone to men but this hormone actually can be found in females as well, although in smaller quantities. The main production of testosterone happens in the testes. The hormone is vital for regulating the male sexual characteristics but also helps in strengthening the bones and building up muscle mass.
  • Estrogen – this hormone is mostly associated with females but is also present in the bodies of males. It regulates the female sexual characteristics and regulates the menstrual cycle but also takes part in the strengthening of the bones.
  • Growth hormone – it is made in the pituitary and stimulates (also regulates) the growth while kids are growing. During the adult stages of life the growth hormone regulates the repair of the bones.
  • Insulin – it’s made in the pancreas and regulates the glucose use and the blood sugar level.


Catabolic reactions break down complex molecules into simple ones. They occur spontaneously and lead to release of energy. Sometimes the catabolism leads to generation of waste products – carbon dioxide, lactic acid (which is the main culprit of the sore muscles during exercise), etc.

Catabolic processes break down proteins into amino acids, polysaccharides (glycogen, cellulose, starch) into monosaccharides (ribose, fructose and glucose), etc.

Catabolic hormones

  • Cortisol – it’s mostly known as “the stress hormone” and is generally released during periods of – you guess it – stress. Cortisol increases the levels of blood sugar, the blood pressure and suppresses the immune processes of the body.
  • Adrenaline – also known as epinephrine. It is most widely known as the culprit of the “fight or flight” response and accelerates the heart rate, dilates (opens up) the bronchioles (which leads to better absorption of oxygen) and boosts up the energy levels by releasing glucose into the blood.
  • Cytokines – regulates the interaction and communication between the cells.
  • Glucagon – it’s produced in the pancreas and stimulates the glycogen to be broken down to glucose. This hormone is stored in the liver and, when necessary, stimulates this organ to catabolize (break down) glycogen into glucose which can be then released into the

How does the metabolism affect your weight?

The weight of your body is the end result of the catabolic reactions minus the anabolic ones – which means that it’s determined by how much energy has been released minus how much energy has been used up. If there is an excess of energy the body stores it as fat or glycogen. If
you want to lose weight you should reduce the intake of energy and increase the use of energy.

Sometimes people refer to the metabolism as “slow” or “fast” but there is no scientific support of the claim that some people’s metabolism is faster than others. Still, there are some metabolic conditions which can affect your body weight. Two of them are hyperthyroidism or
hypothyroidism. The hyperthyroidism is a disorder where the hormones form the thyroid are overproduced and this leads to excessive use of the energy of the body. The hypothyroidism disorder is the opposite – there is underproduction of thyroid hormones and this leads to the gain of weight.

If you have a metabolic disorder it’s almost impossible to change the rate of your metabolism.

But if you want to achieve an ideal body weight you should follow a proper diet regimen and regularly do exercises. You can build up muscle mass by exercising (or dancing, gardening or doing other physical activities) which can help you have a leaner body with less fat. Also, another factor which affects the weight is the quality of the food – stay away from the so called “empty” calories and avoid eating too much sugars and fats because they eventually get stored into the form of fat.

Anabolic and catabolic exercises

The anabolic exercises help you build up muscle mass. An example is the weight lifting. But anabolic exercises are also most of the anaerobic ones – such as jumping rope, sprinting and physical activities which are done with high intensity for a short period of time. By doing such
exercises your body uses up the reserves of energy, increases the muscle mass and strengthens the bones.

The catabolic exercises are mostly aerobic and burn up the fat stores and the calories of your body. Some examples are dancing, cycling, jogging, swimming or any activity performed at moderate intensity for at least 20 minutes. This is important because after 15-20 minutes of
physical activity the body starts using fats as a source of energy.

If you combine anaerobic and aerobic exercises often you can reach a nice body weight and maintain a good health. The best option is to eat a healthy diet and perform regular workouts which include both strength training and cardio exercises.


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