This isn't as straightforward as "fat babies become fat kids." Many thin and average sized adults started out as pudgy babies. And many school-aged children and adults begin struggling with weight gain well after their baby years.
What the researchers found was that the greatest risk for developing obesity was growing across three major percentiles (25%, 50% and 75%) between ages 1 to 6 months old. So those babies who are most likely to become obese by age 11 years are those who start out as relatively small infants ( under 25th percentile or more than 75% are larger than him/her) in the first month of life, but then grows rather fast and tips the tables towards being one of the larger babies (now over the 75th percentile or less than 25% of others are larger than him/her) by the sixth month of life.
So little bitty babies who become big pudgy babies quickly are those most likely to be obese by grade school. The authors have made the connection, but not explained why that trend continues int childhood. This is a multi-factorial issue, with some of the reasons for the relatively fast weight gain outlined by the authors being:
-Less mobility: these babies may be in strollers, car seats or other stationary positions for longer periods of time.
-Over-fed or fed "incorrectly" such as juice in bottles, solid foods introduced early (before 6 months).
Another suggestion offered by consultant pediatrician Dr. Joanna Lewis is for the family to all sit down and eat together, as "research has shown that obesity is less common in children raised in families that have frequent meals together at home."
So without thinking that this research defines or limits anyone's potential for health, instead see this as allowing us to understand how influential to our health early eating and activity habits are. Thank you for reading!