Higher BMI was associated with a lower PSA (p = 0.06). 1,448 (23%) cases of prostate cancer were found (7%). In a multivariable analysis, obesity was found to be not related to overall PC risk (OR, 0.92; 95% CI, 0.79–1.07; p = 0.28) but was significantly associated with lower risk of low-grade PCa (OR, 0.79; 95% CI, 0.65–0.94; p = 0.01) and a higher risk of high-grade PCa (OR, 1.28; 95% CI, 1.01–1.63; p = 0.04). This evidence concerns the gene KLK3 and Obesity.