This increased metabolic rate can also last for a long time after discharge. Another potential ongoing problem is illness and a reduction in feedings as a result. Some children with cerebral palsy also have higher metabolic rates. There are other ongoing problems which might apply, as well. Some children never develop a hearty appetite and may need to be reminded to eat, even as they get older.
Some children get very active and forget to eat or just like to snack.
Some of them will slowly catch up at their own pace. What we don't know is if all of those children will catch up if you just give them long enough. All weighed less than 1000 grams at birth. A few other studies have looked at long term growth. The variability between these studies is most likely due to the small numbers of children in the studies, and most likely the differing nature of the populations of children born in different NICUs.