It is likely to be concentrated sugar. I do not remember the anko but it describes a baby yu inflating to a size bigger than its mother after the anon feed it or injected it with plenty of sugar water. The kicker in the end was when anon noticed that the ko was drawing more of the sweetstuff when it is stressed, he caused the yu to draw its mother's own paste(after stopping to give the baby yu the sugared water) killing the mother.