Unfortunately your mom has bought into all the media stories. There is no point whining at her to change her mind - you'll have to present her with different evidence.

Sit down and say you are really unhappy with your weight and need to switch to a healthier way of eating. DEFINITELY get the book, read it with her. Maybe she'll be interested in doing it too.

If she's still not listening then just do it anyway, you'll just have to demonstrate how healthy it is. Show her your healthy meals. Pepper omelettes, tuna salad, grilled chicken breast with veggies. How can she think that is unhealthy?