I think if you want to "go off piste", then you should, with the proviso that it is only occasionally. My gran always said that "a little of what you fancy does you good", and I'm sure she was right. What's life after all, if we can't indulge ourselves now and then. My sister has spent most of her life saying "No, I'll be good", and denying herself the odd treat in order to watch her weight, whereas I've always thought that life is for living, after all we're only here once. Now we are older we are both about the same build, so all that self-denial was a waste of time. Don't feel guilty - enjoy the moment!