The respiratory system of the body has an output that, when needed, becomes an input.
Imagine the air intake of your car’s engine being the same as its exhaust.
The body needs oxygen to carry out cellular activities. Many of us believe that whenever there is a need, it is enough to simply provide the required substance. But in this specific case—the cell’s need for oxygen—
there is another factor that is just as important:
capacity, or space, for oxygen to be present and used inside the cell.

More clearly: a cell uses oxygen to produce energy, water, yes, water! metabolic water, and carbon dioxide. All three of these products must completely leave the cell so that it can perform its activities again and create space for the next cycle of energy production and oxygen use.
This means that the carbon dioxide produced inside the cell must be efficiently removed so there is room for adequate oxygen to enter.
Since the primary route for carbon dioxide to leave the body is through the lungs, the importance of exhalation becomes clear.
carbon dioxide must be sufficiently cleared from the cell, transported through the blood, and expelled through the lungs.
A complete, efficient, mechanically optimal exhalation fulfills its role by removing carbon dioxide, reducing internal pressure, and restoring cellular capacity. As the internal pressure decreases, the gradient for airflow is naturally established, allowing inhalation to occur effortlessly.
Now consider the body in a state where fat oxidation is occurring at the cellular level, and you are deliberately using the body aerobically so that fat is the preferred fuel.
Compared to carbohydrates and protein, fat metabolism:
• yields the highest energy output,
• produces the greatest amount of metabolic water,
• and generates the largest volume of carbon dioxide.
That carbon dioxide must be effectively removed from the system so the cellular fat-burning “engine” remains ready to continue the work it is intended to do.
Conscious exhalation is the key that keeps the system open, the cells receptive, and the fat-burning process ready to continue indefinitely.
“The views expressed here reflect a personal perspective and theoretical interpretation of human body function and are intended for explanatory purposes only, not as medical advice.”