How do I get my g/f to try to lose weight?

we're in a long term relationship, both overweight, her more than me. i've started dieting/exercising properly (was and still am playing team sports) but all i get from her is lip service saying she'll start tomorrow. i dont want to hurt her feelings, and i love her no matter what, but she's starting to not look as attractive as she used to with the extra weight. i know it makes me sound shallow and all that, but i love her dearly. i've tried coaxing her, promised her i'd buy her treats, tried scaring her about the health effects but nothing is working. i'm finding myself less attracted to her physically as i am to her mentally and emotionally. you can say what you like about me but ladies if it was the other way around you'd say the same thing. any ideas?