Effect of monotherapeutic caloric restriction diet on cardiometabolic parameters in adults with overweight or obesity: Insights from meta-analyses of randomized controlled trials

The cardiometabolic benefits of caloric restriction (CR) often overlap with those of intermittent fasting (IF), creating clinical uncertainty. This meta-analysis updates and refines the evidence on the effects of a monotherapeutic CR diet (MCRD) on cardiometabolic parameters in adults at high cardiovascular risk, compared with a usual diet. A systematic search of four databases through May 2025 identified 17 randomized controlled trials (1066 participants) with low to moderate risk of bias, all involving populations with a mean baseline body mass index ≥ 30 kg/m². The results indicate that MCRD significantly reduced body weight (MD: -6.29 kg; 95% CI: -7.51 to -5.06), waist circumference (MD: -5.09 cm; 95% CI: -6.48 to -3.70), body fat (MD: -4.89 kg; 95% CI: -5.92 to -3.87), central abdominal fat (MD: -0.7 kg; 95% CI: -0.97 to -0.43), and lean body mass (MD: -1.34 kg; 95% CI: -2.14 to -0.53). Significant metabolic improvements were observed, with reductions in fasting insulin (MD: -2.22 μIU/L; 95% CI: -3.83 to -0.61), HbA1c (MD: -0.31%; 95% CI: -0.61 to -0.01), HOMA-IR (MD: -0.97; 95% CI: -1.86 to -0.09), and both systolic (MD: -6.06 mmHg; 95% CI: -9.46 to -2.65) and diastolic blood pressure (MD: -3.79 mmHg; 95% CI: -6.34 to -1.25). No significant effects were observed on lipid profiles, glucose levels, or high-sensitivity C-reactive protein. Meta-regression showed that caloric intake reduction, longer intervention duration, and older age significantly covariate with weight reduction. While beneficial, MCRD requires complementary strategies for optimal health. Further research is needed to clarify its unique mechanisms and distinguish them from the overlapping effects of IF.