Obesity is defined as excess body fat and not only excess weight [1]; consequence of a positive energy balance [2]; and can cause serious health problems for children and adolescents due to the increased risk of cardiovascular disease,
dyslipidemia,
glucose intolerance,
diabetes,
systemic arterial hypertension [3],
respiratory diseases (obstructive airways such as asthma and sleep apnea),
orthopedic and postural disorders,
dermatitis and some types of neoplasias; or to become obese adults more likely to develop such pathologies [4].
In addition to disturbances in the emotional sphere [5],
non-alcoholic fatty liver disease (NAFLD) [6] and atherosclerosis in young people [7].
There is evidence that the atherosclerotic process begins in childhood [8],
progresses with age and exhibits severity directly proportional to the number of risk factors presented by the individual.
This is why it is believed that primary prevention of cardiovascular diseases should begin in childhood,
mainly through the education process for the promotion of cardiovascular health,
with emphasis on the importance of diet and maintaining a regular practice of physical activity for life [3].
In 1997,
the World Health Organization (WHO) formally recognized obesity as a global epidemic [9]; not limited to just one age group or country [2].
Currently,
the type of fat distribution in the body,
especially the accumulation of intra-abdominal fat,
is considered the most important factor in the associations between these clinical entities [6].
Childhood obesity,
the most common pediatric disease [1],
has also become a major public health problem in recent decades,
and the main risk factor for obesity in adulthood [1].
The etiology of obesity is multifactorial,
being involved in its genesis both environmental and genetic aspects [5].
It is believed that the determinants of overweight comprise a complex set of biological,
behavioral and environmental factors that interrelate and potentiate each other [2,
5].
Obesity affects 641 million adults or 13% of the world's adult population and can reach up to 20% by 2025.
Among men,
prevalence was 10.8% in 2014 (about 266 million people); in 1975,
was 3.2%.
In women,
prevalence increased from 6.4 per cent in 1975 to 14.9 per cent in 2014 (about 375 million) [10].
Between 1980 and 1994,
the proportion of children and adolescents considered obese increased by 100% in the United States of America (USA).
It is estimated that 15.3% of American children,
aged 6 to 11 years,
are obese.
The high prevalence of obesity was also observed in populations of developing countries and low socioeconomic level [11].
In Europe,
in the last 10 years,
this disease has increased by 10 to 40% in most countries [11].
In Brazil,
important research carried out by the Brazilian Institute of Geography and Statistics (IBGE),
referring to the years 2008 and 2009,
evidenced an increase in the prevalence of Childhood Obesity [12].
Data from the Food and Nutrition Surveillance System (SISVAN),
referring to the year 2016 [13],
regarding the prevalence of overweight and obesity in children 5 to 10 years of age,
was found to be 15.0% overweight and 14.6% of obesity in the male gender and 15.6% and 11.6%,
respectively,
in the female.
Obesity,
usually assessed by anthropometric measures,
has idiosyncrasies that are beyond common sense.
For example,
individuals with low body mass index may have a high incidence of typical metabolic syndrome (MS) changes [14].
Attention is drawn to the fact that it would not be the excess of total body fat,
but the distribution of this fat that would be related to insulin resistance and,
consequently,
to MS [14].
Over the years,
research has shown that weight gain alone is less relevant than the distribution of body fat in determining metabolic changes [15].
Evidence suggests the importance of measuring abdominal obesity beyond general obesity to assess health risks in the first decades of life [4].
Image exams are the methods of choice for assessing and quantifying visceral fat [14],
since anthropometric measures are indirect measures [2].
In recent years,
ultrasound has been proposed as a noninvasive technique for assessing intra-abdominal fat [16],
as it is a useful method for the determination of visceral adipose tissue [15].
The possibility of measuring visceral fat gives us an important role in the evaluation of MS [14].
Contrasting with the disadvantages of CT,
MRI and anthropometric measurements,
the US has established a simple,
low-cost,
radiation-free method,
free of side effects,
with proven reproducibility and reliability in the quantification of visceral fat [14],
despite the need for specific equipment and well trained observers,
which can be repeated when necessary and on a large scale,
such as population screening [15].
The visceral distance determined by US is strongly related to CT [20].
Thus,
the measure of visceral abdominal fat per US represents an evolution in the diagnosis of visceral obesity [15].
Among its advantages,
we highlight the ability to differentiate intraperitoneal,
preperitoneal and subcutaneous fat accumulation,
besides the innocuity of the exam,
practicality and quickness,
mainly in the evaluation of the pediatric population.