That could backfire at some point. Self image, self worth etc are complicated issues. Same when kids are repeatedly told they are "smart" .... eventually they start getting the idea they don't have to work hard because they know they are smart .... then suddenly they don't do as well as they did, and start thinking they are not smart ... and take the easy way to keep "succeeding", but are now behind and feeling bad. .....
Then there are the parents that make kids finish their meal ... training them to over eat.