Among individuals with a body mass index (BMI) ≥20 kg/m ² , higher BMI was found to be linked with a higher risk of future persistent proteinuria and any proteinuria. This link was noted to be stronger for persistent proteinuria than for any proteinuria.

• This study included 9,320 nondiabetic Japanese middle-aged men who had no proteinuria, an estimated glomerular filtration rate ≥60 mL/min/1.73 m ² , no history of cancer, and no use of antihypertensive medications at baseline.

• Researchers defined “Any proteinuria” as proteinuria identified for the first time during the follow-up period irrespective of its frequency, and “Persistent proteinuria” as proteinuria that was identified at least twice consecutively at annual tests and did not return to negative until the end of the follow-up.

• Both lower and higher BMI were found to be linked with the risk of any proteinuria. In participants with a BMI ≥20 kg/m ² , a higher risk of future persistent proteinuria was observed in relation to higher BMI.

• The relationship between BMI and the risk of persistent proteinuria was identified to be stronger compared to that between BMI and any proteinuria.

• In multiple-adjusted model, for BMI <18.0, 18.0–19.9, 20.0–21.9, 22.0–23.9, 24.0–25.9, 26.0–27.9, and ≥28.0 kg/m ² , the following hazard ratios of persistent proteinuria were estimated respectively: 1.52, 1.07, 1.00 (reference), 1.14, 1.89, 2.12, and 3.85.