To answer this question, first we have to explain to ourselves what metabolism is. It is the machine, the internal combustion engine of our body or the combination of biochemical reactions which supply us with energy to exist – in order our hearts to beat, to breathe, to digest and absorb the nutrients, to work with our muscles, to think and feel emotions.

At subcellular level metabolism represents complex molecular processes of energy transformation from one form into another and at the end production of ATP (Adenosine triphosphate) – the synonym of the word energy in biochemical language, as well as other molecular compounds necessary for the building and maintenance of vital structures. At a cellular level metabolism includes the transportation of nutrients and their selective degradation and conversion into other building elements (hormones, enzymes, structural proteins, etc.)


Metabolism is measured numerically by the amount of energy needed for our existence. Often our body is subject to over-expenditure or state of more active “burning” (catabolism) and then, in order to achieve a balance between the consumed and received energy units (kilocalories or kilojoules), we need more and denser food intake.

This happens in professional athletes, in physiological conditions, such as growth in puberty, pregnancy and breastfeeding in women, in infectious diseases related to increase of the body temperature, in hyperfunction of the thyroid (Graves disease), in diseases associated with impaired food utilization, in insufficient food intake, due to external reasons. In the times of abundance we live in, however, the most common metabolic problem is associated with accumulation of metabolic products in systemic excessive intake of nutrients. As a result, metabolism is shifted towards accumulation, storage of the excess or anabolic state of metabolism. The regulation of these processes is extremely delicate and happens first at the level of brain structures, hypothalamus and pituitary gland where neurotransmitter signaling substances, peptides and hormones are produced, linked with appetite, thirst, thermoregulation, etc.

How the metabolism of our patients works is a question that often is necessary to be answered from almost every doctor, and not only – coaches, fitness instructors, nutritionists and the so called specialists on body proportions, before starting giving nutritional and sports advices. The clients (patients) are usually measured, tested and questioned in order to justify one sufficiently objective and competent assessment and recommendation.


You see that this is not quite a simple task and sometimes it requires more time and patience from both sides. After performing the necessary examinations and instrumental measurements, we have to understand what the biochemistry in the given organism is or in other words said – to measure the concentration of the metabolic products in the blood.

The laboratory data is the most objective indicator of our metabolism and that is why we measure the value of the metabolic products of the three main nutrients – carbohydrates, proteins and fats. The main indicator of carbohydrate metabolism is blood sugar or glucose, and it is often necessary to evaluate it by conducting a test (loading with glucose or glucose tolerant test) and measurement of insulin – the hormone that is responsible for glucose utilization in the cells and its transformation into energy. To evaluate protein metabolism, it is enough to measure creatinine, urea and uric acid. And to measure lipid metabolism, we usually look directly at the blood levels of lipids through measuring the different fractions of cholesterol and triglycerides.

After evaluating the three major nutrients, also called macronutrients, it is often necessary to evaluate the metabolism of some micronutrients in the blood as well – substances which catalyze enzyme reactions and have direct or indirect relationship to the overall metabolism in the organism. These are vitamins (vitamin D, B12, A, E, etc.), minerals (Fe, Ca, Mg, Zn, etc.), electrolytes (K, Na, Cl).

The hormone showing the function of the thyroid – TSH (thyroid stimulating hormone) should not be omitted in anamnestic and clinical suspicion for compromise in its function. It is also important to study the function of the adrenals, secreting the stress hormones, as well as the sex hormones in certain cases.

The overall assessment of metabolism sometimes requires a study of the function of some organs whose function is directly related to the metabolism of macro- and micronutrients. These are the liver and the kidneys.

The clinical assessment of metabolism, as you see, is strictly individual and is often a multi-stage process.

The human body is a dynamic system and every change in the nutritional or motor regimen can have an impact. Sometimes, however, the change in the lifestyle is not enough, and in order to achieve the right effect we need to add medications.

In conclusion, I would like to encourage the people to test themselves on purpose and to approach responsibly and in time every change in their physical characteristics, not to rely too much on the advice of people with non-medical education and to be more reasonable when it comes to their health, especially in the conditions of the vanity we live in today.

For