• Nicole Prince
• Rachel S. Kelly 

Extract

Lung function and development are critical to long-term respiratory health [1, 2]. Identifying modifiable factors, particularly within the early life period, that can be targeted to optimise lung function is therefore a critical priority. Body mass index (BMI) is a well-established risk factor for poor lung function [3], and given the inherently variable nature of BMI, could offer such a target. However, conflicting reports [4–6] from the literature have limited our understanding of the impact of BMI on lung health, specifically with regards to changes in an individual's BMI trajectory over time, which does not necessarily follow a linear or predictable course [7]. Furthermore, the biochemical underpinnings of the purported relationship between BMI and lung health have not been well explored. In this issue of the European Respiratory Journal, Wang et al.