I dont really have a general theory for this but all i can say is if you dont love yourself and be kind to yourself, you will never be entirely kind towards others in the truest spirit – there will always be an element of being critical somewhere down the line.

Thus being kind to yourself is a sufficient condition for being kind to others but it is not a necessary one – some people are very kind to others without necessarily being kind to themselves. That kind of one sided compassion is a manifestation of other problems.