Diagnostic Methods in Childhood Obesity

*Leonardo de Souza Piber, Patrícia Colombo-Souza and Jane de Eston Armond*

#### **Abstract**

Childhood obesity, the most frequent pediatric disease, a worldwide public health problem, is considered a global epidemic and the main risk factor for obesity in adulthood. Among its consequences, cardiovascular and metabolic diseases stand out, which can be diagnosed during childhood, potentiate morbidity and mortality throughout life. Anthropometry, which includes the analysis of body mass index and the measurement of waist circumference, has proven efficacy in pediatric clinical evaluation. However, these diagnostic methods do not differentiate between subcutaneous and intra-abdominal or visceral fat. In this sense, diagnostic imaging methods complement the assessment of abdominal fat. In children, ultrasography appears as an innocuous, reproducible, and reliable diagnostic imaging method. The importance of knowing diagnostic methods for better monitoring of childhood obesity is emphasized.

**Keywords:** pediatric obesity, anthropometry, subcutaneous fat, intra-abdominal fat, ultrasonography, diagnostic methods, diagnostic imaging

#### **1. Introduction**

Obesity can be defined in a simplified way as a clinical condition in which there is an excessive accumulation of body fat, in the form of adipose tissue, and not just excess weight [1], as a consequence of a positive energy balance [2], capable of causing damage to the health of individuals [3], leading to reduced life expectancy [4]. It is known that the etiology of obesity is multifactorial, with both environmental and genetic aspects being involved in its genesis [3, 5].

It is believed that the determinants of excess weight make up a complex set of biological, behavioral, and environmental factors that interrelate and potentiate each other [2, 3].

Childhood is a phase of intense and rapid growth and physical, psychological, and social development, which causes an increase in nutritional needs. The advances in modern life have caused changes in the lifestyle of families around the world, causing these nutritional needs to be inadequately met, through the consumption of high-calorie diets, fats, voracious food, exchanging meals for quick snacks. These factors are linked to physical inactivity, the result of changes in children's games, which currently focus on video games and the excessive use of computers and television [6, 7].

The aforementioned aspects corroborate the increase in the prevalence of childhood obesity, a chronic disease characterized by increased body fat and

influenced by genetic factors that, combined with environmental factors, make it difficult to maintain a healthy weight [6].

Childhood obesity, the most frequent pediatric disease [1] has also become a major public health problem in recent decades, being considered a global epidemic by the World Health Organization (WHO) [8–10], and the main risk factor for obesity in adulthood [1, 2, 10, 11].

Between 1980 and 1994, the proportion of children and adolescents considered obese increased 100% in the United States of America (USA). It is estimated that 15.3% of American children, aged between 6 and 11 years, suffer from obesity. The high prevalence of obesity has also been observed in populations in developing countries and with low socioeconomic status [12].

In Europe, in the last 10 years, this disease has grown around 10–40% in most countries [10, 12]. A study of 9-year-old Irish children found 19.3% to be overweight and 6.6% to be obese. Of children with parents of normal weight, 14.4% were overweight or obese, while 46.2% of children with obese parents were overweight or obese [9].

Parental obesity is well established as an important risk factor for childhood obesity [2]. Having an overweight father doubles the risk of childhood obesity, while obesity between the two parents further increases the risk. The relationship between the weight of the father and the son is complex, as it is a consequence of shared genetic and environmental factors [9].

Brazilian data on the prevalence of overweight and obesity in children aged 12–59 months; of these, 14.7% were overweight and 4.1% were obese [13, 14]. These results, both in relation to overweight and in relation to obesity, placed Brazil as the fourth most prevalent country when compared to 12 other countries in Latin America and with the data of Mexican children residing in the United States of North America [14].

In Brazil, there was an important increase in the number of overweight children in the country, mainly in the age group between 5 and 9 years. The number of overweight boys more than doubled between 1989 and 2009, from 15 to 34.8%, respectively. The number of obese people increased by more than 300% in this same age group, going from 4.1% in 1989 to 16.6% in 2008–2009. Among girls, this variation was even greater (from 2.4 to 11.8%) [15]. Obesity affects about 30% of children, mainly in middle- and high-income families [10].

Excess weight can cause serious health problems for children and adolescents due to the increased risk of cardiovascular diseases [16], dyslipidemia, glucose intolerance, diabetes, systemic arterial hypertension [17], respiratory diseases (obstructive airways, such as asthma and sleep apnea), orthopedic and postural disorders, dermatitis and some types of neoplasms; or even to become obese adults with a greater propensity to develop such pathologies [10, 12, 18, 19]. In addition to disorders in the emotional sphere [3] and non-alcoholic fatty liver disease (NAFLD) [7, 8, 10, 11, 20–22].

The growing trend in childhood obesity is related to the increase in the diagnosis of systemic arterial hypertension in children [6, 17, 23] and atherosclerosis in young people [24]. Metabolic changes resulting from obesity also increase the risk of developing hepatic steatosis [25], which has been proposed as one of the components or the hepatic manifestation of the metabolic syndrome [12]. Hepatic steatosis (HE) has an overall prevalence of 2.6% in children, ranging from 23 to 53% in obese children [10, 25].

NAFLD in childhood reduces life expectancy as it can progress to severe liver dysfunction [11, 22]. It is important to understand the natural history of HE not only because of the risk of progression of liver disease, but also because of the potential association with other pathologies such as type 2 diabetes mellitus and cardiovascular diseases [25].

**87**

to MS [29].

*Diagnostic Methods in Childhood Obesity DOI: http://dx.doi.org/10.5772/intechopen.92880*

factors [17].

activity for life [17, 26].

**2. Visceral fat**

established [29].

Metabolic syndrome (MS), a group of disorders that includes obesity, insulin resistance, dyslipidemia, and hypertension, has been gaining importance due to its association with the subsequent development of cardiovascular disease and type 2 diabetes. The extent of coronary atherosclerosis in children and young adults increases considerably with the increasing number of multiple risk

There is evidence that the atherosclerotic process starts in childhood [21], progresses with age and exhibits severity directly proportional to the number of risk factors presented by the individual. That is why it is believed that the primary prevention of cardiovascular diseases should begin in childhood, mainly through the process of education for the promotion of cardiovascular health with an emphasis on the importance of diet and the maintenance of a regular practice of physical

Pediatricians' attention to the consequences of obesity in childhood and adolescence probably started because of the significant increase in its prevalence in developed and developing countries [12]. In view of the increase in the frequency of overweight and obesity among children and adolescents, the diagnosis of nutri-

Excess body fat (mainly visceral fat) has been associated with increased mortality, as there has been an increase in obesity prevalence rates [14]. It is assumed that visceral obesity is a risk factor for cardiovascular morbidity and mortality [27], regardless

Since then, the relationship between subcutaneous, gluteal-femoral, and visceral

It has been shown that the accumulation of visceral fat is related to the development of steatohepatitis and that this accumulation continuously influences the histological changes in NAFLD, from the beginning of the deposition of fat in the

Both steatosis and abdominal visceral fat are independent correlates of cardiometabolic risk, but the associations are stronger between visceral fat and steatosis [29]. Currently, the type of fat distribution in the body, especially the accumulation of intra-abdominal fat (IAF), is considered the most important factor in the

Evidence suggests the importance of measuring abdominal obesity, in addition

Obesity, usually assessed by anthropometric measurements, has idiosyncrasies that are beyond common sense. For example, individuals with a low body mass index may have a high incidence of typical MS changes. Then, attention is drawn to the fact that it would not be the excess of total body fat but the distribution of that fat that would be related to insulin resistance and, consequently,

Over the years, research has shown that weight gain alone is less relevant than the distribution of body fat in determining metabolic changes [28]. Central obesity, characterized by the accumulation of fat in the trunk and abdomen, has visceral abdominal fat (VAF) as one of its components, whose thickness measurement is of great importance, as it is an indicator of cardiovascular risk due to metabolic

tional status must be part of the routine medical evaluation [11, 15].

of the associated dyslipidemia, hypertension, and diabetes mellitus [28].

hepatocytes to the appearance of inflammatory changes [29, 30].

to general obesity, to assess health risks in the first decades of life [18].

associations between these clinical entities [20].

changes resulting from this fat deposit [30, 31].

fat with the action of insulin has been extensively studied and, today, it can be said that at least the association of visceral fat with the components of MS is well

#### *Diagnostic Methods in Childhood Obesity DOI: http://dx.doi.org/10.5772/intechopen.92880*

*Weight Management*

difficult to maintain a healthy weight [6].

countries and with low socioeconomic status [12].

shared genetic and environmental factors [9].

obesity in adulthood [1, 2, 10, 11].

overweight or obese [9].

North America [14].

influenced by genetic factors that, combined with environmental factors, make it

Childhood obesity, the most frequent pediatric disease [1] has also become a major public health problem in recent decades, being considered a global epidemic by the World Health Organization (WHO) [8–10], and the main risk factor for

Between 1980 and 1994, the proportion of children and adolescents considered obese increased 100% in the United States of America (USA). It is estimated that 15.3% of American children, aged between 6 and 11 years, suffer from obesity. The high prevalence of obesity has also been observed in populations in developing

In Europe, in the last 10 years, this disease has grown around 10–40% in most countries [10, 12]. A study of 9-year-old Irish children found 19.3% to be overweight and 6.6% to be obese. Of children with parents of normal weight, 14.4% were overweight or obese, while 46.2% of children with obese parents were

Parental obesity is well established as an important risk factor for childhood obesity [2]. Having an overweight father doubles the risk of childhood obesity, while obesity between the two parents further increases the risk. The relationship between the weight of the father and the son is complex, as it is a consequence of

Brazilian data on the prevalence of overweight and obesity in children aged 12–59 months; of these, 14.7% were overweight and 4.1% were obese [13, 14]. These results, both in relation to overweight and in relation to obesity, placed Brazil as the fourth most prevalent country when compared to 12 other countries in Latin America and with the data of Mexican children residing in the United States of

In Brazil, there was an important increase in the number of overweight children

Excess weight can cause serious health problems for children and adolescents due to the increased risk of cardiovascular diseases [16], dyslipidemia, glucose intolerance, diabetes, systemic arterial hypertension [17], respiratory diseases (obstructive airways, such as asthma and sleep apnea), orthopedic and postural disorders, dermatitis and some types of neoplasms; or even to become obese adults with a greater propensity to develop such pathologies [10, 12, 18, 19]. In addition to disorders in the emotional sphere [3] and non-alcoholic fatty liver disease (NAFLD) [7, 8, 10, 11, 20–22]. The growing trend in childhood obesity is related to the increase in the diagnosis of systemic arterial hypertension in children [6, 17, 23] and atherosclerosis in young people [24]. Metabolic changes resulting from obesity also increase the risk of developing hepatic steatosis [25], which has been proposed as one of the components or the hepatic manifestation of the metabolic syndrome [12]. Hepatic steatosis (HE) has an overall prevalence of 2.6% in children, ranging from 23 to 53% in obese

NAFLD in childhood reduces life expectancy as it can progress to severe liver dysfunction [11, 22]. It is important to understand the natural history of HE not only because of the risk of progression of liver disease, but also because of the potential association with other pathologies such as type 2 diabetes mellitus and

in the country, mainly in the age group between 5 and 9 years. The number of overweight boys more than doubled between 1989 and 2009, from 15 to 34.8%, respectively. The number of obese people increased by more than 300% in this same age group, going from 4.1% in 1989 to 16.6% in 2008–2009. Among girls, this variation was even greater (from 2.4 to 11.8%) [15]. Obesity affects about 30% of

children, mainly in middle- and high-income families [10].

**86**

children [10, 25].

cardiovascular diseases [25].

Metabolic syndrome (MS), a group of disorders that includes obesity, insulin resistance, dyslipidemia, and hypertension, has been gaining importance due to its association with the subsequent development of cardiovascular disease and type 2 diabetes. The extent of coronary atherosclerosis in children and young adults increases considerably with the increasing number of multiple risk factors [17].

There is evidence that the atherosclerotic process starts in childhood [21], progresses with age and exhibits severity directly proportional to the number of risk factors presented by the individual. That is why it is believed that the primary prevention of cardiovascular diseases should begin in childhood, mainly through the process of education for the promotion of cardiovascular health with an emphasis on the importance of diet and the maintenance of a regular practice of physical activity for life [17, 26].

Pediatricians' attention to the consequences of obesity in childhood and adolescence probably started because of the significant increase in its prevalence in developed and developing countries [12]. In view of the increase in the frequency of overweight and obesity among children and adolescents, the diagnosis of nutritional status must be part of the routine medical evaluation [11, 15].

## **2. Visceral fat**

Excess body fat (mainly visceral fat) has been associated with increased mortality, as there has been an increase in obesity prevalence rates [14]. It is assumed that visceral obesity is a risk factor for cardiovascular morbidity and mortality [27], regardless of the associated dyslipidemia, hypertension, and diabetes mellitus [28].

Since then, the relationship between subcutaneous, gluteal-femoral, and visceral fat with the action of insulin has been extensively studied and, today, it can be said that at least the association of visceral fat with the components of MS is well established [29].

It has been shown that the accumulation of visceral fat is related to the development of steatohepatitis and that this accumulation continuously influences the histological changes in NAFLD, from the beginning of the deposition of fat in the hepatocytes to the appearance of inflammatory changes [29, 30].

Both steatosis and abdominal visceral fat are independent correlates of cardiometabolic risk, but the associations are stronger between visceral fat and steatosis [29]. Currently, the type of fat distribution in the body, especially the accumulation of intra-abdominal fat (IAF), is considered the most important factor in the associations between these clinical entities [20].

Evidence suggests the importance of measuring abdominal obesity, in addition to general obesity, to assess health risks in the first decades of life [18].

Obesity, usually assessed by anthropometric measurements, has idiosyncrasies that are beyond common sense. For example, individuals with a low body mass index may have a high incidence of typical MS changes. Then, attention is drawn to the fact that it would not be the excess of total body fat but the distribution of that fat that would be related to insulin resistance and, consequently, to MS [29].

Over the years, research has shown that weight gain alone is less relevant than the distribution of body fat in determining metabolic changes [28]. Central obesity, characterized by the accumulation of fat in the trunk and abdomen, has visceral abdominal fat (VAF) as one of its components, whose thickness measurement is of great importance, as it is an indicator of cardiovascular risk due to metabolic changes resulting from this fat deposit [30, 31].

Visceral fat can be assessed by measuring waist circumference or by means of imaging tests, such as computed tomography (CT), magnetic resonance imaging (MRI), and ultrasonography (US).

#### **3. Assessment of nutritional status**

The assessment of nutritional status aims to verify growth and body proportions in an individual or in a community, with a view to establishing intervention attitudes. Thus, the standardization of the evaluation to be used for each age group is of fundamental importance, thus standardizing the criteria used by the health team [32].

With regard to the identification of cases of obesity in children, an important issue has been discussed, that is, which is the most accurate method to classify it [6].

When defining methods for assessing the nutritional status, those which best detect the nutritional problem that is intended to be corrected in the study population should be chosen. The costs for its use, the level of personal skill required to apply them properly, the time needed to perform them, the receptivity on the part of the population studied, and the possible health risks must be considered [32] .

Determining obesity is, establishing excess body fat [14]. This concern is justified by the increase in the prevalence of obesity worldwide and the potential risks of developing chronic diseases in adulthood [32].

Among the various methods, anthropometric diagnosis and imaging diagnosis stand out.

#### **4. Assessment and diagnostic anthropometric**

Anthropometry, which consists of assessing the physical dimensions and the global composition of the human body, has proved to be the single most used method for nutritional diagnosis at the population level, especially in childhood and adolescence, due to its ease of execution, low cost, and innocuity. Based on the publications of Jellife, edited by WHO, in the 1960s, based on studies that had started in the 1950s, anthropometry was systematized as a method of assessing nutritional status. It was from these studies that anthropometry developed rapidly in industrialized countries, which only occurred in the mid-1970s in developing countries. Since then, anthropometry has constantly evolved, being a useful method in population, clinical, and intervention studies, and its application has enabled advances in interpretations and in the search for mathematical formulations that improve the accuracy of body compartment estimation and its predictive power. Since 1978, WHO has adopted data from the National Center for Health Statistics (NCHS) as an international reference standard [32].

Anthropometric values represent, at the individual or population level, the degree of adjustment between the genetic potential for growth and the favorable and harmful environmental factors. The ideal anthropometric pattern, then, would be that obtained from populations or ethnic groups whose individuals had enjoyed the opportunity to fully develop their growth potential. In this sense, we use the statistical results obtained from populations in developed areas of the world, or in underdeveloped regions, from human groups of high socioeconomic standard, who probably had better opportunities to fulfill their genotypic growth possibilities [32].

Results from studies around the world have shown and show the possibility of using a single, international benchmark to assess growth and nutrition status in different regions. There is evidence that the growth in height and weight of healthy children of different ethnic origins, submitted to adequate living conditions, is similar up to 5 years of age [32].

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**Figure 1.**

*Geneva (2000, 2006 and 2007).*

*Diagnostic Methods in Childhood Obesity DOI: http://dx.doi.org/10.5772/intechopen.92880*

looking forward in the horizon line.

used method and also the one proposed by WHO [32].

percentiles between 85 (inclusive) and 97 [33–35].

and muscle mass [32].

**4.1 Body mass index**

[2, 6, 27, 36].

illustrated in **Figure 1**.

tile and the Z score [32].

Among the almost unlimited number of possible body measurements, the most frequently used measures are intended to determine body mass, expressed by weight; linear dimensions, especially height; body composition and energy and protein reserves, estimated by the main superficial soft tissues: subcutaneous fat

Anthropometry, then, even considering its limitations, has been the most widely

It is recommended that the weight be measured in kilograms (kg), with an anthropometric scale, with the child barefoot, with light clothing and in an orthostatic position in the center of the scale, and that the height be measured in centimeters (cm), using a stadiometer, to the nearest 0.1 cm, with the child barefoot, with the back to the wall, feet together and parallel, in an upright position and

The body mass index (BMI) is obtained by dividing body weight, in kilos, by height in square meters [2]; therefore, in kg/m2 [33–35], it is an anthropometric measure widely used to identify excess weight in children, adolescents, and adults

The stratification of nutritional status is obtained from the percentiles in the BMI/age ratio according to gender, from WHO, and allows children to be classified as eutrophic, overweight, or obese. Obesity is diagnosed in children with the percentile is equal to or greater than 97 and, overweight, in children with the

The following BMI scores for age are considered, according to the WHO [33–35],

The values of these anthropometric data should always be analyzed according to the child's age and sex, which are the main determinants of its evolution [2]. Although they are usual and simple procedures, they must be applied carefully, with standardization, and the instruments used must be calibrated frequently [32]. Obesity in children is not defined by an absolute number, but by a percentile [2, 37]. To establish a comparison of a set of anthropometric measurements with a reference standard, several scales can be used, the most common being the percen-

The percentiles are derived from the distribution in ascending order of the values of a parameter, observed for a given age or sex; the classification of a child

*Reference values for diagnosing nutritional status using BMI curves for age. World Health Organization,* 

#### *Diagnostic Methods in Childhood Obesity DOI: http://dx.doi.org/10.5772/intechopen.92880*

Among the almost unlimited number of possible body measurements, the most frequently used measures are intended to determine body mass, expressed by weight; linear dimensions, especially height; body composition and energy and protein reserves, estimated by the main superficial soft tissues: subcutaneous fat and muscle mass [32].
