Definition
One speaks of thinness when body weight falls below 90% of that considered ideal based on age, sex, height, constitution and habitual physical activity.
Still others refer to the BMI or body mass index, which considers all people with a weight / height ratio of less than 18 to be lean.
Thinness, even when very accentuated, is not necessarily synonymous with illness. It is therefore important to establish first if we are dealing with constitutional thinness or secondary to physiological causes or pathological causes.
Types of thinness
As mentioned, when we speak of thinness, not necessarily this is associated with pathologies, but it could also be constitutional thinness or thinness secondary to physiological causes (due, for example, to an increase in physical activity or the adoption of a restricted diet).
Therefore, when we speak of reduced body weight it is necessary to make a distinction between constitutional thinness, that is without pathological meaning, and weight loss secondary to diseases or states of malnutrition.
Constitutional raw materials are characterized by a marked generalized reduction of the adipose mass, with a loss of lean mass that is in line with the standards of the long-limbed constitution.
The picture of pathological thinness is rather broad and includes, just to give some examples, endocrinopathies, gastrointestinal diseases, chronic infectious diseases, neoplasms, neuropsychic diseases, forced hypoalination and protracted physical stress.
Thinness in athletes
Among the three definitions given above, the most suitable in sports is undoubtedly the one that refers to the adipose mass of the individual, provided that an appropriate distinction is made between man and woman.
The total fat mass can be divided into two components: the primary fat and the reserve lipids. The first includes the adipose deposits present in the bone marrow, in the lungs, in the liver, in the spleen, in the kidneys, in the intestine, in the muscles and in the central nervous system. Primary fat does not have a simple energy function, but it is biologically essential to support vital vital functions (see: lipid functions). For this reason the primary adipose reserves represent the minimum share of body fat compatible with health. In humans the primary fat is around 3-4% of the total body mass, while in women, by virtue of the adipose reserves necessary to support reproductive functions, this percentage grows up to 12-14%.
Some female athletes become amenorrheic (less than 3 menstrual cycles per year) already at levels of adipose mass lower than 16%, with a substantial loss of bone minerals and with an increased risk of fractures and premature osteoporosis. In humans, when the fat mass falls below 5-6% there is a greater susceptibility to infections.
In reference to an athlete, we speak of thinness when the percentage of adipose mass falls below 5% in men and 15% in women.
Thinness in healthy people
The terms underweight and thin are not necessarily synonymous, just as the terms overweight and fat are not. For this reason the definition of the most appropriate thinness when talking about healthy people is the following:
- In reference to a healthy person, one speaks of thinness when the body weight falls below 90% of that considered ideal based on age, sex, height, constitution and usual physical activity.
It is therefore necessary to choose evaluation criteria that allow us to estimate the weight of the subject, taking into account the various components that influence it. In the article "the ideal weight" we proposed this automatic calculator for adults.
When talking about thinness it is important to also evaluate the medical history of body weight, since rapid and sudden weight losses are more likely to take on pathological connotations.
Pathological thinness
Unlike athletes and healthy people in whom these components are saved, weight loss in pathological thinness is often accompanied by a substantial loss of bone and muscle mass. Think for example of skeletal diseases, characterized by reduced bone mass (osteoporosis, osteomalacia, bone tumors etc.). Under these conditions the previously proposed thinness standards may be inadequate.
A first criterion for assessing the pathological or constitutional origin of thinness is the relationship between appetite and body weight. A constitutionally meager subject subjected to a high-calorie regime, shows considerable resistance to fattening and, despite overeating, its weight remains almost constant. On the contrary, a malnourished individual responds positively to the caloric surplus, increasing in weight.
In the presence of pathological thinness the situation is more complex, since the subject can decrease in weight both due to a significant loss of appetite, and in the presence of appetite and normal or even increased caloric intake.
Diagnosis
Pathological thinness is a symptom of even very serious underlying diseases. For this reason, it is essential to make a timely diagnosis, in order to determine the pathology that triggered it as soon as possible.
In general, we can say that thinness takes on a pathological meaning when :
- Suddenly arises in a normopeso and normoalimentato subject;
- Despite diet therapy, it tends to get stronger with the passage of time;
- It is accompanied not only by a reduction in adipose mass, but also by loss of muscle tissue and, in some cases, bone demineralization.
Once diagnosed the pathological thinness, on the basis of the analysis of the other symptoms presented by the patient, the doctor will then be able to evaluate - with the help of possible additional tests - which pathology has affected the patient.
In the case of thinness sustained by eating disorders, however, the picture is more complicated and dictated by an altered perception of the body image. Anorexia nervosa, in fact, includes a wide variety of symptoms ranging from intense physical activity associated with systemic refusal of certain foods, to resorting to elimination behaviors (self-induced vomiting, diuretics, laxatives, etc.) as a result of copious binges .
Causes
There are many diseases that can cause thinness, each of which is accompanied by its own clinical picture.
If thinness is accompanied by a reduction in appetite, the triggering causes could be diseases such as anorexia nervosa or tumors of the gastrointestinal tract and pancreas.
On the contrary, if thinness is associated with a normal appetite or an increase in it, the pathologies responsible for its appearance could be of an endocrine nature (such as, for example, in the case of hyperthyroidism), pituitary pathologies, diabetes mellitus or l substance abuse (for more information: Thinness - Causes and Symptoms).
Treatment
In the case of pathological thinness, the therapeutic approach to be employed will depend on the underlying pathology that caused it and the timeliness with which it is diagnosed.
For this reason, when you notice an excessive unwanted weight loss and, above all, if it occurs abruptly and suddenly, it is essential to immediately contact the doctor who will take all appropriate measures.
CONTINUE: Diet against constitutional thinness "
