Biomechanics and Health

FOOD, WATER, AIR, PHYSICAL ACTIVITY AND WEIGHT GAIN/WEIGHT LOSS

[Abstract]

As long as we can trace human understanding about food, it was always known that food is essential for the sustaining of life and in the same time, food intake usually leads to weight gain and that the absence or harsh restriction of food intake leads to weight loss.

On the other side, the human understanding always was that some people gain weight more easily and some not so easily and that many never gain excessive weight, regardless of how much food they eat and how much they are physically active or inactive.

The fact is that by some people (“naturally thin people”) food intake doesn’t lead to weight gain.

It means that for naturally thin people, the food together with water and air are essential for the sustaining of life but doesn’t cause weight gain.

It was always a little bit strange that some people always have the same weight at the time when food is available, but people didn’t get a such conclusion that intake of food is not an important factor in weight regulation of the body because on the other side, there were plenty examples of starvation where the absence or harsh restriction of food intake causes weight loss by everyone (by naturally thin, overweight and obese) and when regular food intake leads to weight gain by everyone who had lost weight due to starvation.

The examples of starvation clearly show that extreme reduction of food intake for a considerable amount of time will cause weight loss to the point of skeletal proportion by everyone; it doesn’t mater if he is naturally thin, overweight or obese. (Need to bear in mind that not all people affected by starvation are able to reach the point of skeletal proportion because some of them will die from starvation before they lose significant percentage of their body weight.)

The next fact is based on another example from real life and it shows that if the people affected by starvation to the point of skeletal proportion, get enough food to eat on a regular basis, in short time they will regain weight. That fact strengths the conclusion that still the absence of food intake will cause weight loss and that the food intake will cause weight gain by everyone.

One contradictory fact came from human space travel. Since the beginning of human space travel it was known that the weightlessness alters the regulation of body weight. For the time of being in weightlessness, a human body is affected by atrophy.

In weightlessness the human body is losing muscles mass, bones mass and fat mass. In weightlessness the air, water and food are essential to sustain life but don’t have any significance for weight regulation of the body. A regular or an increased food intake in weightlessness doesn’t cause weight gain for anyone.

Even more striking is the fact that a regular or increased food intake in weightlessness won’t prevent or even slow weight loss (atrophy of the muscle and bone tissues and as well atrophy of the fat tissues). One another important fact is that in weightlessness the human body is losing strength.

For the time of being in an weightless environment, the cosmonauts and astronauts are spending a great amount of time doing exercises on specially designed exercises’ machines and devices and the reasons for that is to slow atrophy of the muscle tissues, fat tissues and bone tissues and in the same time to slow the loss of the body’s strength.

In a weightless environment, the only way to slow atrophy of the body and to the some extent counteract negative consequences for body strength and health caused by the absence of gravity is to provide the body with mechanical stimulations produced by working against the forces of specially designed exercise machines.

Working against the forces of exercise machines and specially designed devices enables us to some extent to slow the loss of the body’s strength. Mechanical stimulations produced by working against the force of the exercise machines and specially designed devices enables (to the some extent) them to counteract the wasting away of the muscles, bones and fat mass. 

On the Earth, the body has weight because of the pull of gravity and the muscles and bones are (for most of the times on subconscious level) used to support the body weight.

In the weightless environment, a body doesn’t have weight and because of that fact the muscles and bones can’t be used to support the body weight.

The reason for the decline of the strength in weightlessness and the reason for decline of the strength on the earth are nearly identical. In a weightless environment the reason for the strength of decline is absence of the use of the bones and muscles (absence of physical activity) and on the earth the reason for strength of decline of the muscles and bones are insufficient use (insufficient physical activity).

The atrophy of the muscle tissues, fat tissues and bone tissues in the weightless environment happen because of the absence of mechanical stimulations on the fat tissues, muscle tissues and bone tissues.

On the Earth, the human body is provided with a few types of mechanical stimulations. One kind of mechanical stimulation is coming from impact forces. The impact forces appear each time when we step with the foot on the ground while walking, running and jumping. These impact forces reverberate from the bottom of the feet through the rest of the body providing mechanical stimulations to the body.

The walk is the act of propelling and transferring the body weight from one leg to the other leg. Walking with unbalanced gait has the consequence of, to some degree, falling from one leg to another and that has the consequence of producing stronger impact forces.

This means that one kind of mechanical stimulations on the body is the product of the impact forces produced by walking, running and jumping.

Another kind of mechanical stimulations is produced by the body’s own weight. Simplified examples are; the upper body weight is providing mechanical stimulations to the legs.

In reality, the weight of each particle of the body that is above is providing mechanical stimulations to the particle that is below.

In a standing position, the weight of the head and neck is providing mechanical stimulation to rest of the body. The weight of the upper part of the body is providing mechanical stimulations to the lower part of the body.

In sitting position, the upper body weight only partly provides mechanical stimulations to the upper parts of the legs and doesn’t provide mechanical stimulations to the lower parts of the legs.

In a position parallel with the ground (laying down position) the upper body weight doesn’t provide mechanical stimulation to the lower part of the body (but still the weight of each particle that is above is providing mechanical stimulations to the particle that is below).

One other fact that needs to be taken into consideration is that in a sitting position we are not using legs to support weight of the upper part of the body against the pull of gravity. Prolonged sitting will lead to decrease of the strength of the legs (due to a lack of use), and the decrease of the muscle, fat and bone mass of the legs (due to insufficient supply of mechanical stimulations).

The act of use of the bones and muscles is a factor that maintains and builds the strength of bones and strength of the muscles. At the same time the weight of the body is providing mechanical stimulations to the bone mass and to the muscle mass and that is one of the factors that maintains existing bone and muscle mass and builds new ones..... .... [The full text of this article is in the Book]