The association between changes in ultra-processed food (UPF) consumption and cardiometabolic risk (CMR) factors remains understudied. We evaluated the association between changes in UPF consumption over 12 months of follow-up and changes in CMR factors in adults diagnosed with metabolic syndrome.We analysed data from 5373 adults (aged 55-75 years) participating in the PREDIMED-Plus trial. Diet was evaluated at baseline, 6- and 12-month visits using a validated food frequency questionnaire, and UPF consumption (in grams/day and percentage of total daily dietary intake in grams) was categorized based on NOVA classification. We used mixed-effects linear models with repeated measurements at baseline, 6 and 12 months of follow-up to assess the associations between changes in UPF consumption and changes in CMR factors adjusting for sociodemographic and lifestyles variables.In multivariable-adjusted models, when comparing the highest versus the lowest quartile of UPF consumption, positive associations were found for several CMR factors: weight (kg, β = 1.09; 95% confidence interval 0.91 to 1.26); BMI (kg/m2, β = 0.39; 0.33 to 0.46); waist circumference (cm, β = 1.03; 0.81 to 1.26); diastolic blood pressure (mm Hg, β = 0.67; 0.29 to 1.06); fasting blood glucose (mg/dl, β = 1.66; 0.61 to 2.70); HbA1c (%, β = 0.04; 0.01 to 0.07); triglycerides (mg/dl, β = 6.79; 3.66 to 9.91) and triglycerides and glucose index (β = 0.06; 0.04 to 0.08).Higher UPF consumption was associated with adverse evolution in objectively measured CMR factors after 12 months of follow-up in adults with metabolic syndrome. Further research is needed to explore whether these changes persist for longer periods.