She said her weight is healthy, and besides, what a person weighs has little connection to a true sense of self esteem. Lots of big people feel just fine about themselves as a person, even if they aren't happy with their weight. Conversely, lots of thin people hate themselves.
Anyway, I think the way to have self esteem is to earn it. I think this is usually done best by finding something outside yourself to devote your energies towards, such as volunteer work or becoming an expert in something meaningful. You need to try to make a difference to OTHER people.
Relax... I'll need some information first. Just the basic facts - can you show me where it hurts?