Tips on gaining weight? My baby is 22 months old and only 19 pounds. She’s in the 2nd percentile and has been since birth. She was full term (born on my due date) she had a dietician for a while but her pediatrician said that was no longer necessary. She eats EVERYTHING and she eats all day long but she still doesn’t gain weight. I even give her a multivitamin and still no improvement.