Purpose <p>Personalized nutrition (PN) shows promise for improving cardiometabolic health; however, evidence on its summarized methodologies and effectiveness remains limited and inconsistent. This review evaluates the effects of PN interventions on cardiometabolic outcomes in adults with overweight or obesity.</p> Methods <p>We searched five databases for randomized controlled trials (RCTs) published up to March 2026. Eligible RCTs included at least one biological component to guide personalized dietary advice. Data were pooled using a random-effects meta-analysis, with heterogeneity assessed by Cochran’s Q statistic and quantified using I2. Risk of bias and certainty of evidence were assessed.</p> Results <p>Fifteen RCTs met the inclusion criteria, each comparing PN with standard, non-personalized dietary interventions. PN implementation varied substantially in the quantity and type of individual-level features, algorithms applied, and personalization strategies used. No significant differences were observed between PN and controls in energy intake or macronutrient composition. 46.7% employed specific dietary patterns as controls or withheld nutritional counseling. Pooled analyses showed slightly greater reductions in body weight and body fat in the PN group compared with controls, but no effects on body mass index, waist circumference, lipid profile, or glycemic markers. GRADE certainty ranged from moderate to very low across the assessed outcomes.</p> Conclusion <p>PN interventions modestly reduce body weight and body fat. Importantly, the absence of a standardized PN framework hampers evaluation and comparison of the effectiveness of nutritional personalization strategies. Future research should aim to establish standardized PN definitions, harmonized individual-level features, and transparent reporting.</p> Registry and registry number for systematic reviews or meta-analyses <p>CRD420251134855.</p>