Background In term-born infants, the risk of developing metabolic syndrome (MetS) has been shown to be associated with formula feeding and early rapid growth. Breastfeeding, however, seems to be associated with a lower risk of MetS among term-born infants. Objective The possible association between type of early nutrition, early growth, and possible influence on different metabolic outcomes at 6 y of age was investigated in very-preterm-born children. Design This study is a 6-y follow-up of 281 very-preterm-born infants with a gestational age of ≤32 wk. Infants breastfed at discharge from the hospital were randomly assigned to receive unfortified or fortified mother's milk, whereas those who were not breastfed received a preterm formula. The intervention lasted until 4 mo of corrected age. At 6 y of age, height, weight, and body mass index were measured and a dual-energy X-ray absorptiometry scan and blood sampling were performed. Results In total, 239 children participated in the follow-up. No differences were found between the 2 breastfed groups. Formula-fed children were more often predisposed to obesity and from families with a lower social status than were children who were breastfed only. Early rapid growth (crossing of weight percentiles with >1 SD in either direction) was seen in 53% of the children from 34 wk of postmenstrual age and until 2 mo of corrected age and was significantly correlated with several metabolic outcomes at 6 y of age. Conclusions Children fed a preterm formula postdischarge more often showed early rapid growth than did breastfed children, and early rapid growth was correlated with early signs of MetS at 6 y of age. However, all of the values were within normal ranges. This trial was registered at as NCT02078687.