Babies who do not put on much weight in the first few months of their lives reach the same weight as their peers by age 13.
A study published in the journal Pediatrics warned against giving small babies a bigger calorie intake, as this may increase the chance of obesity.
Lead researcher Professor Alan Emond said: “For health professionals, the point is that for a child that is well with no symptoms they can be relaxed and not worry about pushing calories because you can push them the other way."
Weight data for close to 11,500 infants was analysed by researchers from the University of Bristol.
The results suggest that by age 13, small babies had a similar BMI and waist circumference to their peers.
Before the age of 13, however, they remained lighter and shorter than the control group.
Professor Emond noted that feeding habits in the second six months of life can determine a child’s future weight gain.
He said in many cases slow growth can be caused by children who follow their genetic potential, rather than the “standard curve”.