Comparative effects of ketogenic diets and mediterranean diets on obesity and metabolic outcomes: a systematic review and meta-analysis.

Ketogenic diets (KD) and Mediterranean diets (MD) are among the most widely studied dietary approaches for obesity and metabolic disorders; however, their comparative efficacy remains controversial. This systematic review and meta-analysis aimed to compare the effects of KD and MD on anthropometric and metabolic outcomes in adults. A comprehensive search of original databases was conducted from inception until March 2026. Randomized controlled trials comparing KD with MD in adults were included. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were calculated using random-effects models. KD significantly reduced body weight (WMD: -3.56 kg; 95% CI: -5.62, - 1.49), body mass index (BMI) (WMD: -1.86 kg/m²; 95% CI: -2.73, - 0.98), waist circumference (WC) (WMD: -4.25 cm; 95% CI: -7.46, - 1.04), total body fat (TBF) percentage (WMD: -2.09%; 95% CI: -3.98, - 0.20), and insulin levels (WMD: -3.15 µU/ml; 95% CI: -5.02 to - 1.28) compared with MD. In contrast, no significant differences were observed between KD and MD regarding fasting blood sugar, HbA1c, LDL-C, HDL-C, triglycerides, systolic blood pressure, diastolic blood pressure, or C-reactive protein levels. However, KD significantly reduced total cholesterol (TC) compared with MD (WMD: -9.71 mg/dl; 95% CI: -17.79, - 1.62). Publication bias was detected for triglycerides and LDL-C outcomes. KD demonstrated superior effects on anthropometric outcomes compared with MD, particularly for weight loss and body composition improvement. However, both dietary approaches showed largely comparable effects on glycemic control, lipid profile, blood pressure, and inflammatory biomarkers. While KD may provide greater short-term weight reduction, MD may remain a sustainable dietary strategy for long-term cardiometabolic health.