Objectives To test the hypothesis that greater weight fluctuation between 2 and 6 years is associated with an increase in weight measures (such as body mass index [BMI]) and cardiometabolic risk in young adulthood. Study design Weight fluctuation (determined by BMI SD scores) was measured at least 3 times between the ages of 2 and 6 years in 166 girls and 116 boys from the Terneuzen Birth Cohort. Cardiometabolic risk factors in young adulthood include components of the metabolic syndrome and weight. The extent of weight fluctuation was determined by assessing each individual's SE (or variation) around each individual's linear regression slope (or weight slope). The obtained variation scores were subsequently related to adult BMI, other weight measures, and cardiometabolic risk factors. Results In girls, greater weight fluctuation between 2 and 6 years was statistically significantly related to greater adult weight measures (1.08; 95% CI 1.01-1.15) and nonsignificantly with the metabolic syndrome. For boys weight fluctuation was not associated with adult weight (1.04; 95% CI 0.97-1.11), but weight slope was statistically significantly associated with adult overweight. Conclusions The results suggest that weight fluctuations during early childhood are predictive for adult overweight in girls. For boys weight slope instead of weight fluctuation is predictive for adult overweight.