Sun Y, Milne S, Jaw JE, et al. - Researchers analyzed data from published clinical trials to examine the link between BMI and the rate of forced expiratory volume in 1 s (FEV₁) decline in COPD. They carried out a systematic review of the literature and found 5 randomized controlled trials assessing the link between BMI and FEV₁ decline. They performed meta-analyses including 4 of the identified studies. Four classes of BMI were analyzed: BMI-I (< 18.5 or <  20 kg/m²), BMI-II (18.5 or 20 to < 25 kg/m²), BMI-III (25 to < 29 or < 30 kg/m²) and BMI-IV (≥ 29 or ≥ 30 kg/m²). A meta-regression of all the estimates against the BMI category was also conducted. In COPD, the obesity paradox is supported by these new revelations: low BMI vs normal BMI was identified as a risk factor for accelerated lung function decline, while a protective influence of high BMI was evident. The link may be because of common but as-of-yet unrevealed causative factors.