Pooling randomized controlled trials comparing ketogenic (KD) and Mediterranean diets (MD) head-to-head in adults, this meta-analysis found KD produced significantly greater reductions in body weight (−3.56 kg), BMI (−1.86 kg/m²), waist circumference (−4.25 cm), total body fat (−2.09%), and fasting insulin (−3.15 µU/mL). KD also outperformed MD on total cholesterol reduction (−9.71 mg/dL). However, the two diets were statistically indistinguishable on fasting glucose, HbA1c, LDL, HDL, triglycerides, blood pressure, and CRP — the very markers most predictive of long-term cardiovascular risk.
The headline numbers favor keto, but the clinical story is more nuanced. The weight advantage — roughly 3.5 kg — is meaningful for short-term obesity management yet modest over a lifetime. More telling is what KD did *not* improve: glycemic control and lipid-cardiovascular markers remained equivalent to MD, a diet with decades of mortality and cardiovascular outcome data supporting it. The insulin reduction in the KD group is biologically plausible but did not translate into glycemic superiority as measured by HbA1c. Publication bias was flagged for triglycerides and LDL, the two outcomes where KD skepticism is greatest — a notable caveat. Adherence data, the Achilles heel of KD trials, was not synthesized. For adults choosing a long-term dietary framework, the finding suggests KD may accelerate initial weight loss but MD's sustainability advantage and its established longevity evidence base remain compelling counter-arguments. Incremental rather than paradigm-shifting.