Objective: study aimed to clarify the effect of weight loss on pulmonary function test (PFT) in ILD patients with obesity. Methods: In a case-control study, 76 patients with bladder cancer with IL-1B-511 biallelic polymorphism were included, the number of tandem repeats was genotyped. Results: Among all consecutive ILD patients with a body mass index (BMI)27 kg/m2 who received nutrition education for improving obesity between June 2018 and December 18, we retrospectively included patients who successfully decreased their body weight by over2 kg and underwent follow-up PFT within 6 months. The results of PFT at baseline and follow-up and the level of Krebs von den Lungen-6 (KL-6) were compared.A significant association was found between IL-1 polymorphism and an increased risk of recurrence in patients with urothelial bladder cancer. There was no significant relationship in patients with G1. Carriers homozygous for IL-1B-511T / C had an increased risk of recurrent bladder cancer with odds ratios 2.7 (95% confidence interval [CI], 1.5-4.9) and 3.1 (95% CI, 1.5. –6.5) respectively. Statistical analysis showed an interaction between the two loci with risk associated with IL-1B. The -511T allele increased significantly (odds ratio, 9.0; 95% CI, 3.5-23.0). Conclusions. In ILD patients with obesity, weight loss is important and potentially improves their disease course.