My mother was on diet ..she lost 9 kg...now she wanted to keep her weight ..what can she do?

Eat a healthy diet!: It is typical for people to regain the weight they lose from a diet once they go back to the way they ate before the diet. For your mother to maintain weight loss she must continue to eat a healthy diet (though not as strict as her weight loss diet). Exercise helps too. See http://bit.Ly/1dhw9ht for a healthy diet that is sustainable- she does not need to follow it strictly but tend towards it.