I dont think it should matter to you weather she wants to lose the weight or not ... your doing this for her own well being. She will realize eventually. My mom put me on diets and im happier now... When she realizes how much better she feels about herself shell thank you. if she still doesnt wanna do it well then you should just "happen to change" the family's eating habits... she will eventually figure it out but if you cook the meals theres nothing she can do about it