Hi 54 , in the early days I was very strict in checking daily calories and frequently incorporated OMAD one meal a day when I was working which worked for me . Nowadays I think more in terms of staying low carb rather than low calorie because it is the insulin response and the fluctuating blood sugars which muck everything up . Your body cannot use your fat stores for fuel if your insulin levels remain high .
I think you have to find what works for you but trying to move away from sugar is a good plan in the first instance . Bananas would be too high in carbs for me, (17g carbs) for a medium banana . I have a book called “The carb and calorie counter “which has visuals of foods and their carb and calorie counts and it was a revelation.
It’s not that any food is ‘banned ‘ but if you choose the more sugary fruits you are likely to keep your insulin levels high . I used to pile my blender with all sorts of fruits and seeds every morning and thought I was doing the right thing but my weight only started to come off ( after years of serial dieting ) when I moved to low carb, reading Jason Fung’s books and realising how damaging sugar had been to me .