The growing increase in the prevalence of childhood obesity and overweight is considered a public health problem.1, 2 In their recently published study, Lobstein et al. estimate that by 2025, some 268 million children worldwide between the ages of 5 and 17 could be overweight.3 In Spain, more than one third of the child population is overweight, and most studies determine higher prevalences in ethnic minorities.4, 5, 6

Obesity is a complex disorder involving interwoven biological, family and environmental factors.7, 8 The environmental factors include changes in the diet, a sedentary lifestyle and the abuse of screen time. However, neither should the less-studied sociocultural factors, which can also be determinants of excess weight in childhood and adolescence, be forgotten.4, 5 These include both the acquisition of the eating habits of the society of origin together with others from the adoptive society and the abuse of ultra-processed products, which promote a positive energy balance with an increased sedentary lifestyle. Moreover, immigrants from developing countries do not perceive excess weight as a concern, but associate it with health, greater social status and prosperity.4 For all these reasons, the parents' origin can act as an independent risk factor, as the prevalence of excess weight in the children of immigrant mothers in Spain is higher than that of native children.4 In fact, in Spain few studies have analysed the relationship between ethnic influence and overweight or obesity in adolescence.4, 9, 10, 11

The migratory phenomenon is one of the most significant demographic events to have occurred in our country in recent decades. The immigrant population is currently comprised of more than 5.4 million people. In areas such as the Region of Murcia and Melilla, this group accounts for over 15%–20% of the population, with even higher figures in rural areas. The most numerous groups of immigrants come from South America, followed by those from North Africa and other European countries.12 In view of this social phenomenon, our studies must include the most vulnerable group of immigrant children. The main objective of this study was therefore to analyse excess weight figures in native adolescents and in the children of immigrants and to ascertain the ethnic influence on lifestyle habits which may lead to overweight and obesity.