BREATH THAT CALCULATION!

The ability to fairly estimate the energetic cost of an activity or existing in a certain physiological state, can be achieved via the relationship between oxygen consumption (how much oxygen is used in the body's cells), and how much energy investment does every unit of oxygen consumption represent.

As explained in a previous blog post about the metabolic equivalent (MET), constants are great news and tools in the service of science. We scientists LOVE constants because they make our job and life much easier, and also makes it easier to explain, teach, lecture materials and knowledge to you. Do you sense an explanation about a scientific constant coming? - True that!

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Accordingly, every litter of oxygen consumed (1,000 mL; or 34.5 oz; or 0.27 American gallons; or 0.2631 imperial gallons) represents an energetic expenditure (investment) of 4.83 kilocalories (Kcal; big calories). this constant makes it easier to calculate or estimate a person energy expenditure, if you know or can estimate their oxygen consumption.

The average person consumes about 250 mL of oxygen every minute they are alive and at complete physiological rest. 250 mL are the same as 0.25 litters, thus, the average person consumes about 1/4 of a litter of oxygen every minute they are alive and at complete physiological rest. Since every whole litter of oxygen consumed means an energetic investment of 4.83 Kcal/L, than via mathematical extrapolation, 1/4 litter of oxygen consumed equals an energetic investment of 1.2075 Kcal per minute.

Now that we know how many calories a person invests at rest per minute, let the calculation commence! - Accordingly:

The average person invests 72.45 Kcal to be in complete physiological rest for an hour (60 minutes; 1.2075 Kcals X 60)

The average person invests 1738.8 Kcal to be in complete physiological rest for an entire day (1,440 minutes; 1.2075 Kcals X 1,440)

Even the slightest movement, activity, or exercise beyond complete physiological rest, will increase the energy investment

In another blog post called "burning fat explained" I indicated how much oxygen is needed to burn one pound of fat. You can now understand how I calculated that, since dividing the number of Kcals in one pound of fat (3,500) by the number of Kcals in one litter of oxygen consumed (4.83 Kcal/L) equals about 725 litters of consumed oxygen required.

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