To the reader:

I think you could try to teach your friend about enjoying healthy food. It only works if you are subtle, so work in small steps. Try inviting her over for dinner and cooking a healthier version of pizza or lasagne or some other food she might recogize. Or take her out for a healthy but filling meal at a good quality restaurant (Italian is often good for this). By doing this the aim is to lead by example: show her that healthy food tastes great, fills you up and can contribute to a fun meal, as well as being good for you. Then she will see that living a healthy lifestyle needn't be torture, in fact it is something that a lot of people (chefs, gourmet food lovers, etc.) deliberately seek! Good Luck!