Weight regulation

Carbon-diOxide is perceived by many as a light, almost weightless gas, but it’s relatively heavy. Trees grow slowly to weigh hundreds of kilos or even tons. More than half of their weight comes from Carbon which they patiently extract from the Carbon-diOxide they ‘inhale.’

Humans inhale the relatively light Oxygen, and exhale the heavier Carbon-diOxide; this is how they lose actual body weight.

Gasses and food-fuels

Gasses, solids, and liquids continuously go in and out of my body. Some of the food and gasses I intake my body can use, but some are unusable and need to be disposed of. My lungs deal with the gasses, and my digesting system with solids and water.

To better understand body weight changes, I separate all that I ingest into three groups:

  1. Useable materials.
  2. Unusable stuff.
  3. Body water.


Useable materials

My digesting system breaks down the useable materials I eat and drink into:

  • Sugar and Fat – burnable food fuels.
  • Proteins – building blocks (they are also burnable).
  • Minerals and vitamins.


After the initial breakdown, a conversion process is needed for efficient burning. For example, different Carbohydrates are converted into body-Sugar, and fat is converted into body-Fat.

These converted food fuels are constantly fed to my body cells, which extract energy from them, mainly by ‘burning’ in the presence of Oxygen, but also, to a limited extent, by fermenting them without Oxygen.

Some organs in my body ‘operate’ exclusively on body-Sugars, for example, my brain. Other organs, like my heart, function best when it burns body-Fat.

It’s relatively easy for my body to convert sugar into a burnable body-Sugar. Body-Sugar activates powerful reward mechanisms in my brain, which makes me want more & more & more of it.

My body’s ability to store body-Sugars for future use is poor, but it can do that well with body-Fat. Therefore surplus body-Sugars are converted into body-Fat, which is a form of energy reserve.


Unusable stuff and water

I eliminate the unusable stuff in the toilet (poop). It contains water, fiber, bacteria, and other foodstuffs I failed to chew.

My body uses water for chemical processes, conversions,  cleaning, and cooling. Some of the water I discharge when urinating. There are also some solids in my urine, but otherwise, it’s mostly water. More than 50% of my body weight is water. I can’t afford to go below a certain minimum of body water reserves.

How did the C get there?

Inhaled air consists of

80% Nitrogen + 20% Oxygen.


Exhale air consists of

80% Nitrogen + 16% Oxygen + 4% Carbon-diOxide.


The question is, where did the added Carbon in the exhaled air come from?



  • ‘Inhale’ Carbon-diOxide through their surface.
  • ‘Drink’ water using their roots.
  • Absorb energy from the sun using their ‘solar panel’ leaves.






Trees use the solar energy they absorb in their leaves to break the Carbon-diOxide they inhale. Then they release the Oxygen into the air and keep the Carbon. Next, absorbed solar energy is used to break the water trees ‘drink’ into two parts of Hydrogen and one part Oxygen. In the final stage, solar energy bonds Carbon to Hydrogen and Oxygen, creating organic building blocks. Millions of combinations of these building blocks allow a fantastic variety of plants and trees. Sugar, Carbohydrates, Fat, and Proteins are examples of these organic building blocks found in foods. Food fuels hold energy and contain Carbon. During the ‘burning’ process in my body, the Carbon from the food fuels bonds with Oxygen turning into Carbon-diOxide, and the bound energy is released. Finally, I exhale the Carbon-diOxide, and the energy is used to power my muscles and heat my body.


Body-Fat has allowed humans to survive food shortages throughout their evolution and wander around without a constant need for ‘refueling.’ It was useful when we were hunters and gatherers, constantly looking for food. Then we settled down and started cultivating and growing foods. As a result, our diet has changed. The new diet allowed us to quickly ‘charge our batteries’ with foods rich in sugar and processed flour. The way we activate the body has also altered. People became heavier as their bodies kept storing Fat. Today in our industrialized world, more people are dying due to over-eating than food deficiency. Sadly, too many people eat ‘digestible stuff’ rather than nourishing food. This abundance of low-quality foods, coupled with lifestyle changes, is one of the causes of obesity, which is now a world epidemic.

Up until not so long ago, being overweight was considered healthy, and people made efforts to gain weight. The concept was that having reserves during a food shortage improves survival chances. Body fat also became a status symbol. However, following a concept revision, being overweight is now widely regarded as an overload on the body. As a result, many people have set themselves a goal to lose weight. In some cases, it’s justified, but definitely not in all.

There needs to be a negative food-fuel balance to lose weight; in other words, we need to eat less than what we burn. Drastically cutting down on eating is challenging because of our strong instinct to ‘refuel.’ Being overweight is not easy, and so is losing weight.

Weight changes calculations

It is convenient to distinguish between body weight and actual body weight to better understand how weight is lost or gained.

  • Body weight includes usable material, unusable stuff, and water.
  • Actual body weight is only the useable materials.


My body weight increases when I eat and drink. It decreases by sweating, urinating, exhaling water vapors, and eliminating. My breathing regulates my actual body weight. The calculation below shows how it works. The values used are rounded & averaged.

The volume of my tidal breathing is about 0.5L (0.13gal) of air, weighing 0.6gr (0.0013lb); I breathe about 22.000 times daily.


22.000 X 0.6 = about 13Kg (28lb).


So, every day I take into my body about 13kg (28lb) of air. Roughly every 50 days, I consume solid foods (usable and unusable, excluding water) equal to my body weight, which is about 60kg (140lb).


60 ÷ 50 =~1.2kg (2.6lb).


So, every day I take in about 1.2kg (2.6lb) of solid food. The air going into my body every day weighs much more than my daily food intake.

The air that I exhale is heavier than the air that I inhale. That is because Carbon-diOxide is heavier than Oxygen, which adds about 0.01gr (0.000022lb) to every exhale. This additional small fraction may seem insignificant, but when multiplying it by the number of times I breathe every day, 22.000, it becomes big.


0.01 X 22.000 = 220gr (0.5lb) per-day.


So, on average, I lose 220gr (0.5lb) of actual body weight daily because of the difference between inhaled and exhaled air weight.

One way I can lose actual body weight is to ensure I supply my body with fewer food fuels than it burns. My body will then revert to its body-Fat reserves, and with time I can reduce my actual body weight by about 220gr (0.5lb) every day. When I exercise aerobically,  my daily weight loss is even higher because that increases the number of my breaths. For example, if my breathing increases to 33.000 times a day when I work out, I would lose 330gr (0.7lb) every day.


0.01 X 33.000 = 330gr (0.7lb) per-day.


It may seem that if I sit down and hyperventilate, I will clear more Carbon-diOxide from my body and lose more of my actual body weight. That is, of course, not the case; in fact, people who unconsciously hyperventilate tend to be overweight.

When hyperventilating, levels of Carbon-diOxide in my bloodstream drop, my blood vessels constrict, and as a result, less Oxygen and food fuels get to the cells. In order to lose actual body weight, there needs to be a sufficient supply of Oxygen and food fuel to the cells. Without burning food fuels, there is no way to lose actual body weight.

Burning fat

During exertion, when my muscles are active, my body prioritizes body-Sugar over body-Fat for the burning process. Burning body-Sugar requires less Oxygen than other food fuels and is more effective for intensive muscle use. When there is not enough body-Sugar in the bloodstream, my body resorts to its reserves of body-Fat.

As my body burns body-Fat, heat and mechanical energy are released to power my muscles. While body-Fat has weight, heat and mechanical energy are weightless. Weight can’t just transform into energy or disappear; it’s always conserved.


The question is, where does the weight go when I burn body-Fat? Here is an example:


To burn 10kg (22lb) of my body Fat 29kg (64lb) of Oxygen is needed.

The burning process of body-Fat in the presence of  Oxygen produces 28kg (62lb) of Carbon-diOxide and 11kg (24lb) of water.


10kg (22lb) body-Fat + 29kg (64lb) Oxygen = 28kg (62lb) Carbon-diOxide + 11kg (24lb) Water.


The equation shows that weight is preserved after the burning process.