Aim The aim was to determine body composition and growth in preterm infants based on two different feeding regimens and to assess how standard and individual fortification (IF) affect energy and protein intake. Body composition was assessed at full term and at four months corrected age. Methods Sixty preterm infants born before gestational week 32 were randomized either to IF of mothers breast milk after it had been analyzed or to standard fortification (SF) of mothers breast milk based on the average protein and energy content of breast milk. Body composition was measured at full term and at four months corrected age, using air displacement plethysmography. Growth rate and nutritional intake analyses were also conducted. Results At 40 weeks gestational age, there was no difference between weight (g) (IF 3056 +/- 472 vs. SF 3119 +/- 564), body fat (%) (IF 19 +/- 3.3 vs. SF 21 +/- 5.6), fat mass, or fat-free mass between the two groups. Furthermore, there was no difference between the groups in weight, length, head circumference, or body composition at four months corrected age. Conclusions Fortification based on breast milk analysis may not improve growth in preterm infants compared to SF. However, both groups were smaller and had a different body composition at term corrected age compared to infants born at term.