Metabolic energy: what it is and how it influences health

A living being is a material set of complex organization that exchanges matter and energy with the environment in an orderly manner. To be considered as such, a living entity must be capable of translating the energy consumed from the environment into growth, relationship and reproduction, with the ultimate goal of leaving their genetic imprint on future generations throughout coast.

Living beings (specifically humans) are a continuous exchange: we produce heat, consume oxygen, we release carbon dioxide, and we process organic matter at all times of our lives. Therefore, we have a series of mechanisms that allow us to maintain body homeostasis, or what is the same, an internal balance despite environmental changes. In summary: we are alive because we self-regulate beyond the parameters that surround us.

All these concepts can be reduced to their minimum expression, which is a cell dividing by mitosis and giving rise to a new lineage or, failing that, replacing tissue that has been damaged. To understand all these basal mechanisms,

It is necessary to be clear about a series of concepts, the most important being those related to the definition and functionality of metabolic energy.. Stay with us, because we will tell you everything about her in the following lines.

• Related article: "Basal metabolism: what it is, how it is measured and why it allows us to survive"

What is metabolic energy?

Metabolism is defined as the quality that living beings have of being able to change the chemical nature of certain substances.. On a practical level, this set of processes is essential for cells to grow, divide, maintain their structures over time, and respond to stimuli, among other things.

The “problem” is that, for the production of movement or the synthesis of macromolecules, the cell bodies require energy. So that, the behavior of living beings is coded (to a large extent) based on obtaining energy from the environment, so that your cells can use it to give rise to the relevant biochemical reactions and physicochemical processes.

Based on all these processes, a series of immovable generalities can be established. Among them, we find the following:

• Cells associate reactions: processes that release energy (exergonic) allow reactions that require energy (endergonic) to take place.
• Cells synthesize carrier molecules that capture energy from exergonic reactions and carry it to endergonic reactions. ATP is a clear example of this.
• Cells regulate the speed of chemical reactions through enzymatic activity.

The ATP molecule draws our attention in particular. (adenosine triphosphate), as it is used by cells to capture, transfer, and store the free energy needed to perform chemical work. Understanding metabolic energy without ATP is an impossibility, since this molecule functions as a clear currency of exchange at the energetic level.

What is metabolic energy translated into?

For its part, metabolic energy can be understood as that which It is generated by living organisms thanks to chemical oxidation processes (at the cellular level), product of the food they eat. This parameter can be understood in different ways, but we find it more useful to apply it to the daily reality of human beings. Go for it.

Basal metabolic rate (BMR)

The basal metabolic rate (BMR) is the minimum amount of metabolic energy required by the body to stay alive. In a state of rest, although it may not seem so, your body is consuming 60 to 75% of the calories ingested, because it requires that energy to keep the heart pumping, so that you can breathe and, even, so that the mind can function properly.

In the basal state, the human brain can consume about 350 calories a day, that is, 20% of the BMR. It is not surprising that we feel tired after a long day of study, because, literally, this organ is a true focus of burning fat and other energy resources. In addition to thinking, breathing, and blood pumping, metabolic energy is also used in cell growth, body temperature control, nerve function, and contraction muscular (both voluntary and involuntary).

This value can only be reliably calculated by a nutritionist, as it depends on factors intrinsic to the individual and certain environmental parameters. However, a rudimentary estimate can be obtained using the following equations:

• BMR in men = (10 x weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5
• BMR in women = (10 x weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161

Total energy expenditure (GET)

The total energy expenditure is similar to the basal metabolic rate, but in this case the physical activity carried out by the individual is taken into account.. We do not necessarily understand "physical activity" as running in a marathon, since working standing up at a bar counter, doing waiter or simply walking to a specific place is an additional effort beyond the maintenance of functions vital.

In addition to physical activity, total energy expenditure also takes into account endogenous thermogenesis (TE), which in turn encompasses the thermic effect of feeding (ETA). This last parameter reflects the energy needed to digest, absorb and metabolize nutrients. In this case, the metabolic energy directed to the process and obtained from it depends on the nature of the food and its mixtures in the diet, but it accounts for approximately 10% of the total energy consumed.

Thus, we can collect all the terms encompassed so far in a simple equation, which reflects where does the metabolic energy obtained after ingesting organic matter from the environment go:

Total energy expenditure (100%): Basal metabolic rate (70%) + physical activity (20%) + endogenous thermogenesis (10%)

Again, it is necessary to emphasize that these values ​​vary widely between individuals. For example, a very sedentary person will expend 10% of energy in non-voluntary physical activity (getting up, going to the shopping or walking to work), while an athlete will use 50% of the calories consumed to exercise their muscles and body.

In addition to this, it should be noted that the basal metabolic rate decreases by 1-2% for each decade after the age of 20. So, statistically, an 80-year-old person at rest will burn fewer calories than a 20-year-old, simply because of his physiology and slowed metabolism.

• You may be interested in: "The Most Important Cell Parts and Organelles: A Summary"

Metabolic energy in other animals

Human beings tend to pay attention to our species, but we must not forget that what has been described so far is applicable to all homeothermic living beings., that is, one that can maintain a body temperature despite environmental changes (mammals and birds).

Beyond numbers and percentages, it is truly interesting to know that animals carry out a clear exchange when it comes to obtaining metabolic energy. For example, when a cheetah hunts a herbivorous mammal, it is expending an astronomical amount of energy during the chase in order to find prey. Worth?

The theory of optimal foraging (TFO) is a predictive model of behavior that tries to explain the behaviors of living beings based on this premise.. This postulation announces the following: to maximize fitness, an animal adopts a strategy of foraging that provides the highest benefit (energy) at the lowest cost, maximizing net energy obtained.

Thus, an animal will not eat anything that causes it to expend more energy searching than it gains from consuming. Maybe now you understand why, for example, some huge predators (like bears) completely ignore small birds. flying birds and other vertebrates belonging to the microfauna: it is simply not worth trying to hunt them at a level energetic.

Summary

As you have been able to verify, the theme of metabolic energy ranges from ATP and the cell to the behavior of living beings. Organisms are open systems and, as such, continuously exchange matter and energy with the environment. Therefore, we adapt in order to maximize the effectiveness of our habits, in order to stay longer and increase the chances of survival.

In the end, everything can be reduced to a scale: if what is obtained weighs more than what is spent, it is usually viable at an evolutionary level. If something does more good than harm, it often helps animals survive another day so they can reproduce.

Bibliographic references:

• Bonfanti, N., Fernandez, J. M., Gomez-Delgado, F., & Pérez-Jiménez, F. (2014). Effect of two hypocaloric diets and their combination with physical exercise on basal metabolic rate and body composition. Hospital Nutrition, 29(3), 635-643.
• Gutierrez, G. (1998). Foraging strategies. Handbook of Experimental Analysis of Behavior, 359-381.
• Redondo, R. b. (2015). Energy expenditure at rest. Evaluation methods and applications. Rev Esp Nutr Comunitaria, 21(Suppl 1), 243-251.
• Vazquez Cisneros, L. C., López-Espinoza, A., Martínez Moreno, A. G., Navarro Meza, M., Espinoza-Gallardo, A. C., & Zepeda Salvador, A. Q. (2018). Effect of feeding frequency and timing on diet-induced thermogenesis in humans, a systematic review. Hospital Nutrition, 35(4), 962-970.