# Validation of a Useful Tool for Screening for Overweight and Obesity in Pre-Adolescents
## 1 Introduction  
In the 21 st century, overweight and obesity are common epidemics in developed countries and are increasingly present in developing countries and during economic transition [1; 2]. Currently, according to the World Health Organization (WHO), more than 41 million children under 5 years are overweight or have obesity, and more than 340 million people between 5 and 19 years have overweight or obesity worldwide. Their incidence and prevalence have increased worldwide [3]. The drastic rise in the prevalence of childhood overweight and obesity in recent years is due to significant changes in lifestyle and eating habits in childhood, as well as the promotion of an obesogenic environment that promotes and further encourages the incidence of obesity [4]. Regarding their relationship with other diseases, overweight and obesity in adulthood constitute a chronic pathology that presents greater comorbidity when it is more severe; in relation to the distribution of body fat, the risk of developing diseases such as type 2 diabetes mellitus, insulin resistance, dysplasia, respiratory deficit, hypoventilation, arterial hypertension, coronary heart disease and hyperuricaemia, among others increases [5]. However, since childhood is a stage of growth and development at all levels, more nutrients are needed in relation to the adult stage. There may be a risk of malnutrition due to deficiency or excess when there is restricted access to food, or if a food pattern based on ultra-processed products is followed. An increase in overweight or obesity is a risk factorfor cardiovascular diseases. There are several proven associations between markers of cardiovascular risk, such as biochemical parameters (triglycerides, total cholesterol, insulin, glucose), as well as diet and physical activity. There exist studies on childhood overweight and obesity, however, more consistent information on cardiometabolic and inflammatory risks during this period is required [6; 7]. Among markers of cardiovascular risk, diet represents a significant modifiable risk factor for the etiopathogenesis of obesity. Dietary patterns, as well as habits of life, can be assumed to be both a risk or a beneficial factor at the cardiovascular level and are strictly related to obesity and other cardiovascular diseases [8; 9]. During childhood and adolescence, there are many physiological and psychological changes that influence behaviour and lifestyle in the medium and long term. In childhood, variations in the development and growth between girls and boys appear. Thus, in boys, the age range in which the outbreak of puberty growth begins is from 10 to 15 years, however, in girls, it goes from 8 years to 13 years. These outbreaks of puberral growth differ in the speed of growth as well as in body size and weight gain [10]. There are also significant differences in growth physiology regarding body composition development with respect to sex. A study carried out with 888 children aged 6 years from the UK and India showed significant differences with respect to the percentage of body fat; boys had 4.5% more body fat than girls [11; 12]. A study carried out in the Spanish state in 2015, the ALADINO study (Alimentacion, Actividad Fisica, Desarrollo Infanti y Obesidad--Food, Physical Activity, Child development and Obesity) [13], was carried out with 10,899 boys and girls aged between 6 and 9 years, with the aim of measuring childhood overweight and obesity in school, and a high percentage of overweight and obesity was observed in the age group prior to the sample of this study. The overweight percentages observed in boys and girls between 6 and 9 years old were 22.4 vs. 23.9%; that is a difference of 1.5% attributable to sex for the same age group. However, for obesity, values of 20.4 vs. 15.8% with respect to sex were observed. These data show a difference of 5.2% in obesity with respect to sex for the same age group.