However, it is unclear whether an isocaloric protein-restricted diet affects IGF-1 and IGFBPs in men with prostate cancer.<h4>Methods</h4>In this academic, single-center, parallel-group, prospective, randomized, open-label, blinded end-point trial, 38 consenting overweight (BMI 30.5 ± 5.5 kg/m<sup>2</sup>) men with localized prostate cancer, aged 43-72 years, were randomized (1:1) with permuted blocks to 4-6 weeks of customized isocaloric PR diets (0.8 g protein/kg lean body mass) or their usual diet. The gene discussed is IGF1; the disease is Familial prostate cancer.