How to turn a sinking ship?

I am reading a book by Dr John Briffa called Escape the Diet Trap which deals with the effects of carbs on our fat cells and how insulin works. He is saying exactly what you did. Fats are necessary and are not entirely bad for you, but carbs are. The effects on/of cholesterol are discussed too.

The harm comes from highly refined foods, artificial sweeteners etc. If we ate more unprocessed foods we would be a lot healthier.

You are right to be questioning the current advice.

I feel sure my T2 diabetes has been brought on by a sedentary job which included high stress levels and not enough time to 'unwind' properly (be active) And this addage 'If you are of a certain age and overweight you will develop T2 diabetes' - in my opinion you are overweight because you already have a level of diabetes for your body to contend with. I have never eaten rubbish foods like Big Macs and KFC's, I could not afford to but did use a lot of 'filler' foods like porridge and other carbs. I would have been a lot better eating fats, which in those days was a big No, No.