The thing is Steve that dieticians are not very helpful. They don't seem to be of one mind on this subject.
That's why Helen's answer was so valuable. It reflected my own confusion and had the warmth of human experience.

Most dieticians don't look as though they have eaten anything more substantial than a stick of celery since early childhood.

Since getting Helen's messages, I have bought Mosley's talking book and am halfway through it. I have sent for his book on Amazon.

Its given me a lot of advice, which I pray god will be more helpful than the dieticians who have been put in charge of me and have not helped very much. It was an expensive operation I have had, and really it required aftercare which never arrived. I reallise the NHS is is is in turmoil with the Covid crisis. But I'm having my own little crisis. And sincerely I do appreciate you guys giving me some advice. Including you, Steve.