RATIONALE Epidemiological studies have reported on the detrimental effects on lung function after natural, thus limited, weight gain in time in unselected populations. Studies on bariatric surgery, on the other hand, have indicated large improvements of lung function after substantial weight loss. OBJECTIVE To study the associations between a profound weight loss or gain and pulmonary function within the same population. A second objective was to investigate the effect of weight cycling on pulmonary function. METHODS We selected records from our lung function database, on subjects in the follow-up of CPAP therapy for sleep apnea, with a weight change ≥ 20 kg within 5 years. Lung function (n= 255) at baseline was normal, except for a tendency of mild restriction in morbid obesity. Within this selection, 73 subjects were identified with significant "weight cycling", defined as a ≥ 10 kg opposite change in body weight prior to or following the ≥ 20 kg weight change. RESULTS Weight change affected pulmonary function more in males than in females (p< 0.001). In males, FVC increased on average 1.4% predicted/BMI after weight loss, and the reverse after weight gain, whereas females exhibited a smaller change of 0.9% predicted/BMI. Weight loss slightly increased the FEV1/FVC-ratio and decreased the specific airway resistance, whereas the opposite occurred with weight gain. Larger effects of weight change on lung function were observed in leaner subjects (p= 0.02) and in older subjects (p< 0.002). Changes in TLC followed that of FVC with no change in RV, while the largest change was observed in FRC. In subjects with weight cycling, the improvement in lung function due to weight loss was reversed by subsequent weight gain and vice versa. CONCLUSION This study provides evidence that the detrimental effect of obesity on lung function is a passive and reversible process.

中文翻译：

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体重变化和体重循环对超重和肥胖成人肺功能的影响。

基本原理 流行病学研究报告称，未经选择的人群体重自然增加（因此有限）后，会对肺功能产生不利影响。另一方面，减肥手术的研究表明，大幅减肥后肺功能得到了很大改善。目的 研究同一人群中体重大幅减轻或增加与肺功能之间的关联。第二个目标是研究体重循环对肺功能的影响。方法 我们从肺功能数据库中选择了接受 CPAP 治疗睡眠呼吸暂停的受试者的记录，这些受试者在 5 年内体重变化≥ 20 kg。基线时的肺功能（n = 255）正常，但病态肥胖有轻度限制的趋势。在这一选择中，73 名受试者被确定为具有显着的“体重循环”，其定义为在 ≥ 20 kg 体重变化之前或之后体重发生 ≥ 10 kg 相反变化。结果 体重变化对男性肺功能的影响大于女性（p < 0.001）。在男性中，体重减轻后，FVC 平均增加了 1.4% 预测值/BMI，而体重增加后则相反，而女性则表现出较小的变化，为预测值/BMI 0.9%。体重减轻会略微增加 FEV1/FVC 比率并降低特定气道阻力，而体重增加时则相反。在较瘦的受试者 (p = 0.02) 和较年长的受试者 (p < 0.002) 中观察到体重变化对肺功能的影响更大。TLC 的变化跟随 FVC 的变化，RV 没有变化，而 FRC 的变化最大。在体重循环的受试者中，体重减轻导致的肺功能改善被随后的体重增加所逆转，反之亦然。结论 这项研究提供的证据表明，肥胖对肺功能的有害影响是一个被动且可逆的过程。