Doctors have put Santiago on a strict diet, saying he needs to lose nearly 40 pounds to reach a healthy weight of 17 pounds.
The child will be taken off formula milk and fed primarily vegetables and juices.
Santiago's mother, Eunice Fandino, sought the help of a charity that tackles obesity in Colombia after she noticed the baby had problems moving about due to his weight.
Doctors say there isn't a medical reason behind Santiago's weight gain. He apparently was just overfed.
