Is obesity related to the lung function of non-asthmatic children?

Abstract

Overweight and obesity are highly prevalent in developed and developing countries among children and adolescents. During the last two decades, it became evident that excess weight is adversely related to respiratory health in childhood and adolescence mainly in terms of asthma occurrence. Additionally, there is a mounting body of evidence that overweight/obesity may also affect lung function in non-asthmatic subjects. The aim of this review was to present and discuss the studies that investigated this issue in non-asthmatic children and adolescents. Only a few studies have evaluated the impact of excess weight on static volumes and their results point towards an inverse relationship between overweight/obesity and functional residual capacity. More studies have been conducted on the impact of excess weight on dynamic lung volumes with inconsistent, however, results. Nevertheless, a relatively consistent finding was that the ratio of forced expiratory volume in 1 s/forced vital capacity was significantly lower among overweight/obese children compared to their counterparts with normal weight. The underlying mechanisms of these observations have not been adequately elucidated but it is believed to result from complex interaction of mechanical, developmental, and metabolic causes. There is a need for more well-designed studies in order to clarify the impact of excess weight on lung function in non-asthmatic subjects, as well as to explore the contribution of factors such as duration and degree of obesity, and fat distribution. Despite the absence of conclusive data, there are still convincing evidence to be communicated to the children and their families as part of the arguments to encourage them to adopt a healthier lifestyle.

Keywords: Obesity; Lung function; Spirometry; Lung volumes; Plethysmography

Core tip: We herein present an overview of the existing studies regarding the influence of excess weight on static and dynamic volumes of lung function in otherwise healthy children and adolescents. Although the existing data, are to some extent, conflicting, it seems that in this age group, obesity is correlated to a significant, though not necessarily clinically important, decrease of forced expiratory volume in 1 s/forced vital capacity ratio and a reduction of functional residual capacity. These observations are of clinical relevance, as they may be the origin of respiratory problems in adulthood, especially if obesity persists till then.