When my 7 year old SWCAH daughter was 8 months she was hospitalised for "failure to thrive", meaning she was not gaining weight and had even lost a bit.  Her Endo wanted to check everything out - blood levels etc.  I was still breastfeeding and thought maybe she wasn’t getting enough milk but she refused to take a bottle, she was a little bit fussy with her eating as well with me feeding her.  Her results all came back fine and we finally solved the problem with her feeding herself.  She really didn’t like me feeding her, she was much happier eating soft foods cut up which she could pick up and eat herself.  Soon after we also had her drinking milk out of a cup.  We always said that she "hated" being a baby and wanted nothing to do with baby stuff.    After a little while the weight started going back on and she hasn’t looked back as far as weight is concerned.