I would say they lack protein, because meat is the main source for protein in a persons diet, and if thats taken away then you have to find new ways to get that protein back. Like with eggs and nuts, etc. -hope this helps :3
Maybe try drinking things lie smoothies so that you would probably have the mentality that it is a drink however it is also feeding you and filling you up so try nd have a go at drinking things like smoothies (thickshakes)
