Shang Y, Zhou H, Hu M, et al. - Given the controversial effect of diet on insulin resistance (IR) in polycystic ovary syndrome (PCOS), researchers sought to assess whether diet could reduce IR in women with PCOS while providing optimal and accurate nutritional advice for clinical practice. The quest was performed through June 30, 2019, in eight databases. In total, 19 trials (1,193 candidates) were involved. The analysis demonstrated that diet was significantly linked to improvements in IR and body composition [eg, homeostasis model assessment of insulin resistance, fasting insulin, fasting plasma glucose, body mass index (BMI), weight, and waist circumference] in patients with PCOS. The Dietary Approaches to Stop Hypertension diet and calorie-restricted diets may be the best choices for reducing IR and improving body composition in the PCOS population, respectively. Diet was also advantageous for weight loss (including BMI and weight) and had the same effects on insulin regulation compared with metformin. According to this systematic review and meta-analysis, diet is an effective, acceptable, and safe intervention to relieve IR, and professional dietary advice should be provided to all patients with PCOS.