Eating disorders in childhood and adolescence

Instituição: Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, Brasil 1Graduanda em Nutrição; Bolsista do Programa Especial de Treinamento (PET) em Nutrição, UFSC, Florianópolis, SC, Brasil 2Doutora em Ciência dos Alimentos pela Faculdade de Ciências Farmacêutica da Universidade de São Paulo (USP); Professora do Departamento de Nutrição e Programa de Pós-Graduação em Nutrição da UFSC, Florianópolis, SC, Brasil 3Doutor em Doenças Tropicais pela Faculdade de Medicina de Botucatu, Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP/Botucatu); Professor do Departamento de Nutrição e Programa de Pós-Graduação em Nutrição da UFSC, Florianópolis, SC, Brasil 4Doutora em Ciência dos Alimentos pela UFSC; Professora do Departamento de Nutrição e Programa de Pós-Graduação em Nutrição da UFSC e Tutora do PET Nutrição, UFSC, Florianópolis, SC, Brasil ABSTRACT


Introduction
Eating behavior is defined as "sequential or behavioral answers associated with the act of eating, manner or mode of eating, rhythmic patterns of feed" (1) .Such behavior is influenced by social, demographic and cultural conditions, by the individual perception, the food, previous experiences and the nutritional status (2) .Among these factors, the socio-cultural impact on dietary intake and the development of eating disorders (ED) has been more frequently studied, assessing the family customs (3)(4)(5)(6) and the information conveyed by the mass media (7)(8)(9)(10) .
The influence of the media, magnified by globalization and society, was described by Anschutz et al (7) and Oliveira and Hutz (11) , who emphasize the contradiction between the appeal for healthy lifestyle at the same time that it is praised the cult of thinness and it is encouraged the consumption of high-calorie foods.
The result of these contradictions is the development of ED, characterized by an exaggerated concern with weight and shape (11) .In pursuit of this stereotype, weight loss is induced by inadequate methods, like fasting and intense physical exercise, and gain muscle mass is stimulated by excessive workouts, improper diet and the use of anabolic steroids (12) .
Eating disorders are related to clinical complications that vary according to the characteristics of the disorder, occurring stunted growth (13) , cheilosis, dental erosion, periodontitis, salivary gland hypertrophy, hypovolemia, electrolyte imbalance and weight gain (14) .
When the beginning of ED occurs during adolescence, such disorders affect social and family relationships, and suicidal ideation becomes more common (11,15) .The onset of sexual activity before 16 years-old is also more frequent in adolescents with eating disorders.Moreover, young women with a history of ED have higher chances of abortion or pregnancy (16) .
Thus, this study aimed to discuss the characteristics and the risk factors associated with eating disorders in children and adolescents.

Data Sources
The search for articles was performed in PubMed and SciELO databases, combining the terms 'children', 'adolescents', 'eating behavior', 'eating disorder', 'bulimia' and 'anorexia', both in Portuguese and in English.We considered articles published between 2007 and 2011, and 49 of them were selected.They analyzed the development of eating behavior and its disorders, the anorexia nervosa (AN), the bulimia nervosa (BN) and non-specific ED.

Development of eating behavior and its disorders
The comprehension of eating behavior requires questioning and reflection on the following question: "Who eats what, when, where, and why?".The discussion that arises from this question is based on psychological and health issues, besides those involving socioeconomic factors, as well as marketing (2) .
Studies have shown the influence of family environment to determine the behavior of children and adolescents (3)(4)(5) and, consequently, the development of their disorders, for which the child or the adolescent has a high concern with weight and body shape (12) .This relationship was evident in an European multicentre study developed with 1,664 children and adolescents.This research showed a negative association between the maintenance of a healthy diet and the subsequent development of eating disorders, and a positive relationship between excessive control, the application of strict dietary rules and the individualization of food with the emergence of ED (3) .
The individualization of meals by family memberswith consumption of different foods in different places and times (5) -may be the result of excessive activities among adolescents (3) or the eating disorder within the family (5) .These findings are consistent with those observed in a study of 10,540 pre-adolescent girls.In this study, the habit of dining with family, on most days, was negatively associated to the first use of purging methods, the binge eating disorder and diets (4) .About the family environment, a work showed that there was a greater internalization of the ideal beauty by children when mothers encouraged weight loss (7) .
The mass media have a strong influence on eating behavior in children (6) , as well as in adolescents (10) .The role of the media, ideal beauty and fashion industry in the development of ED is not clear (7,9) .In this context, a study of 245 pre-adolescent girls showed a positive relationship between the habit of watching soap operas and music channels with food restriction and body dissatisfaction, and negative relationship between the habit of watching cartoons and food restriction (7) .Another research among 7,172 adolescents found an association between the desire to appear as a media figure of the same sex with the start of purging behaviors (17) .
As for boys, eating attitudes and disorders are also associated with the evolution of weight, psychosocial well-beingpromoted by food (18) -, the strong appeal of socio-cultural worship of thinness (10) , the social group to which one belongs (19) , besides socioeconomic (10,20,21) and psychological (7) factors.
Eating disorders are more often found in women (22,23) .Some risk factors for the development of these disorders become more prevalent with the increase in body mass index (BMI), as well as low self-esteem, dieting, interceptive deficits, fear of maturity and body dissatisfaction (22) .The concern with weight (22) , diets, weight-related teasing (17,24) and obsessivecompulsive disorder (23) are also associated with ED symptoms.
Recently, a research of 53 women aged between 14 and 44 years-old, diagnosed with diabetes mellitus type 1, also showed that there is a relationship between this disease and the development of disorders such as anorexia nervosa and bulimia nervosa.The authors concluded that women diagnosed with diabetes mellitus type 1, aged from 7 to 18 years-old, were more likely to develop ED (25) .
Risk factors for the development of eating disorders were studied in 652 female adolescents.Among the girls that were evaluated, 25.2% of them were at risk, and 1.2% showed high possibility of developing ED.The desire to lose weight was prevalent in 44.5% of the adolescents, and 50.5% wished to be classified below the ideal weight, according to the BMI.In this study, although the desire for weight loss was independent from socioeconomic status, the prevalence of risk behaviors was superior among individuals belonging to the higher strata (26) .

Anorexia nervosa and bulimia nervosa
Among the diseases of unknown etiology that interrelate with each other, there are the AN and the BN.They are both characterized by abnormal patterns of eating behavior, weight control and altered perceptions about weight and body (27,28) .
In these kind of eating disorders, the concern with food is common.In the study of Nunes and Vasconcelos, for seven adolescents with AN and BN, eating would refer to something negative, such as torture, fear and obligation.Still in the same study, food consumption was characterized by the restriction of "junk foods", e.g.chocolates and candies, and by the increased intake of vegetables and soft drinks (29) .
Anorexia is an eating disorder characterized for the desire for thinness, what leads to dull and ritualized food behavior (27) , and a significant weight loss, especially in children or adolescents in whom low caloric intake is reflected in developmental delay (12) .
The criteria for diagnosing anorexia, defined in the Diagnostic and Statistical Manual of Mental Disorders -IV (DSM-IV), include: amenorrhea, weight below 85% of the minimum expected for age and height, disturbances in recognition of own weight and intense fear of weight gain (12,27) .
The restrictive anorexia nervosa limits energy intake and the consumption of carbohydrates and lipids (27) , while in the purgative one, frequent episodes of binge eating and purgation (30) occur.The purging behaviors are the use of laxatives, diuretics and enemas, and induced vomiting (12) .
The psychological state, in this clinical condition, has been studied in a representative sample of adolescents in the United States.The authors concluded that there was no correlation between the AN and mental comorbidities, except for the 'oppositional defiant disorder'.Once mental comorbidities are highly prevalent in anorexic adults, the study suggested that the occurrence of ED in adolescence may be a causal factor of such comorbidities in adulthood.
In the same research, it was found a statistically significant relationship between BN and depression, bipolar disorder, anxiety related disorders -such as social phobia and posttraumatic stress -, besides behavioral disorders, e.g.hyperactivity, attention deficit and conduct disorders (15) .
The relationship between anorexia and bulimia has been reported in literature (30)(31)(32) .A prospective study of 2,881 adolescents showed that the previous diagnosis of AN and BN was present in 24% of patients with subclinical BN, and in 31% of those with clinical BN (32) .
The bulimic also feel a great fear of gaining weight (27) , and often has a distorted view of one's own body (27,33,34) .These individuals also tend to restrict their food intake, but after some time following a restrictive diet, they lose control and have binge eating episodes (12,27) .After the binge, the bulimic tries to compensate the high caloric intake (12) .Bulimia nervosa can be classified according to the compensatory method, adopted in purging or non-purging (12.27) .The non-purging subtype is characterized by intense physical activity or by fasting (12) , whereas the purging one, more prevalent in the study of Keski-Rahkonen et al (32) , characterizes by induced vomiting or laxative and diuretics abuse (12) .According to DETM-IV, someone is only diagnosed with BN if he/she presents binge and compensation episodes twice a week for at least three months (12,27) .
Bulimia was found most frequently in the age group from 16 to 20 years-old (32) .The authors noted that, due to the similarity between bulimic and non-bulimic BMI and weight maintenance, the person can hide the disorder for several years (32) .
The use of substances that cause addiction are also relevant in adolescents with eating disorders.A prospective study with 999 adolescents found that those who had subclinical AN and BN cases were twice as likely to reach adulthood depending nicotine, with disorders related to alcohol or amphetamines (16) .Another research showed a positive relationship between the use of substances that cause addiction, during adolescence, in clinical cases of BN (15) .Finally, a study observed a weak -but positive -connection between alcohol consumption and smoking with diets, binge eating and extreme behaviors for weight loss (19) .
Even though both diseases normally begin during adolescence, for some authors, anorexia can be found from seven years of age (35) .They point out that AN, in childhood, can affect or even stop physical development, and that the incidence in boys may be higher before puberty.On the other hand, BN is rare before adolescence (35) .
The incidence of AN and BN in childhood is unknown, due to the tendency to group children and adolescents (35) .In adolescence, a study found prevalence of AN equal to 0.3%, and of BN equal to 0.9%, and such disturbances started on average with 12.3 and 12.4 years-old, respectively.Although apparently these prevalences are low, it should be noted that these data may be underestimated because of the refusal of individuals with disorders to participate in researches (15) .
In Brazil, there are few works that determine prevalence of ED in children and adolescents.In 2008, a study, conducted in Florianopolis, of 1,219 girls from 10 to 19 years-old showed a prevalence of AN of 15.6%, and 18.8% of body dissatisfaction.Furthermore, the presence of AN had statistically significant relationship with body dissatisfaction, overweight and obesity in those who studied in public schools and aged between 10 and 13 years-old (36) .Also in the same city, another study of 258 girls found a prevalence of 25.3% of body dissatisfaction, and symptoms of AN and BN of 27.6% (37) .

Non-specific eating disorders
Non-specific ED (EDNOS) are the clinically relevant ones that do not meet criteria for AN or BN (38) .Although its prevalence is higher than that of AN or BN (39) , the knowledge about prevalences, risk factors, clinical correlations and treatment of such disorders is limited (38) .
Among EDNOS, there are the subclinical AN and BN, binge eating (clinical or subclinical), purgation (clinical or subclinical) and others, which include EDNOS that do not fit into the described subtypes (39) .
The frequency of EDNOS in a sample of 281 adolescents referred for treatment of ED was 59.1%, which shows the clinical and epidemiological importance of these disorders.In this study, 16.4% of adolescents were diagnosed with purging disorder, 16.4% with subclinical AN, 11.7% with subclinical BN, and 2.1% with binge eating.Other types of EDNOS had a prevalence of 11%, with cases of purgation, exaggerated practice of exercises and 24 hours fasting.The research showed that 67.4% of patients with subclinical AN were not diagnosed because of the absence of amenorrhea, and the remaining ones for weighing between 86 and 90% below the ideal minimum for age and height.Regarding the subclinical BN, 73.5% of patients did not complete the criteria, due to the lower frequency of binge eating episodes (39) .
Binge eating is a EDNOS that is characterized by ingestion of a greater amount of food that most people ingest in a small time interval, at least twice a week, for six consecutive months, accompanied by a feeling of lack of self-control (40) .During these episodes, individuals feel a loss of control over what or how much they eat and, in the end, they feel guilty and depressed (40) .Unlike the BN, during the binge eating, methods to compensate the excessive amount of food eaten are not used (41) .Although it often does not complete the diagnostic criteria defined for adults, the binge eating is common in children, especially in the obese ones (35,42) .Subclinical cases of such disorder can also occur, in which the feeling of lack of self-control is present in the absence of an excessive consumption (43) .
In a study with adolescents, the prevalence of clinical cases of binge eating was 1.6%, and of subclinical ones, 2.5%.Both of them had the median age of the first symptoms in 12.6 years (15) .
Psychological stress may be associated with the development of binge eating (24,42) .The negative affect and provocations based on weight were related with this disorder in a study of 265 twin sisters.The authors suggested that 'provocations' were the causes of negative affect, and that this stress would initiate the chain of events that leads to binging (24) .
According to the study by Allen et al (42) , food restriction, low self-esteem, depression and concern with weight, body and food are more prevalent in children with binge eating.The relationship between these symptoms and binge eating is directly related to the severity of eating disorder, as observed in a study of 350 children and adolescents with overweight (44) .
Since the loss of control is one of the main characteristics of EDNOS, only a few investigations have exclusively addressed this aspect (43,45) .The study of 120 children -with and without loss of control over food -showed that those with low control over food were more impulsive and had lower self-orientation, low cooperativeness and higher demand for novelty (46) .
The dietary intake of these people has also attracted the interest of some authors.When comparing 59 compulsive children with a Control Group, it was observed that the consumption of carbohydrates and lipids was higher during binge episodes than during normal meals of the Control Group (47) .A study of 249 children and adolescents showed that there has only been an increase in the carbohydrate consumption, with higher consumption of snacks and desserts (48) .
Assessing 259 children, researchers also found that, in EDNOS, there is a relationship between dietary intake and mood, i.e., it was common to use food intake to regulate mood (42) .However, another study of 46 girls from 6 to 12 yearsold with overweight showed no relationship between consumption and binge eating and between consumption and mood after control variable, according to BMI (49) .For other authors, the loss of control was not preceded by negative emotions and negative mood states were not observed after the binge episode (47) .
The purging disorder is a poorly studied ED.In it, the person uses purging behaviors such as vomiting and the use of laxatives and diuretics, without the binge eating necessarily preceding the purgation.In clinical cases, the episodes occur on average twice per week for three months; in subclinical cases, there is not a frequency and duration criterion (39) .
Great attention has also been given to subclinical cases of anorexia and bulimia, because in addition to being more prevalent than specific disorders (15) , studies show that, despite not fulfilling the criteria for the diagnosis of specific disorder or not being persistent, these cases are characterized by the same markers of severity than clinical cases of AN and BN (15,16,28,39) .
A comparative summary of the analyzed studies, with its main findings regarding the characteristics of the disorder and eating behavior in children and adolescents, identified a similarity between age, cause of the disorder and consequences (Table 1).
We discovered few national studies on eating disorder in this study.Considering the importance of the social environment in the development of ED and the specific socio-cultural realities, risk factors found in the works may not apply to the Brazilian case.Also, studies that discussed EDNOS -whether national or international -were rare, which may have limited the debate around the topic.

Conclusions
Among the risk factors for eating disorders, the most significant were the media and the social and family environments.The influence of the media and the social environment was associated, mainly, to the worship of thinness, while in the family, the timing of the meals was essential in determining the eating behavior and the development of disorders.The ED were associated with nutritional problems (stunted growth and weight gain), oral health (cheilosis, dental erosion, periodontitis and salivary gland hypertrophy) and social harm.Swanson et al (15) United States of America n=10,123 (13-18 years-old), adolescents AN, BN, EDNOS, social harm, and suicidality and emotional harm AN (0.3%), BN (0.9%), binge eating (1.6%).EDassociated to social harm, harm in family relationships and suicidal intent BMI: body mass index; SCA: substance causes addiction; PA: physical activity; BI: body image; FR: food restriction; FB: feeding behavior; ED: eating disorder; AN: anorexia nervosa; BN: bulimia nervosa; EDNOS: non-specific eating disorder; ED+: eating disorder diagnosed in adolescence; SA: sexual activity; P: purgative; SCBN: subclinical bulimia nervosa; FM: familiar meals.

Table 1 -
Key findings of the analyzed studies PA, fast-food and breakfast, time -TV, meals -family FM: <binging, purgation and overweight.Female: purgation is related to diets and the media (3.7%).Compulsive eating is related to parents: female (7.1%); male (2%) BN, SCBN, age, gender, weight, ethnicity BN is more related to social class, appearance, fear of negative evaluation.BMI is related to socio-cultural factors.