My 2 year old son (saltwaster) seems to have a hollow leg..........  he would much rather drink milk/juice than eat!  He is only in the 15% for height, but I am only 5’2 and my husband is only 5’6 so it is hard to tell.......  my 8 month old son (also a saltwaster) is in the 5% for height-

Gwen