My husband and I have been on the 5;2 diet for a year now. We are strict on diet days, eating nothing until tea time but drinking plenty of water and, in my case tea with skimmed milk. Even on holidays we have managed to stick to two diet days a week.(Quite an achievement on cruise holidays!!!!!) and are both down to target weights with BMI of about 22.
We find that as long as we don’t gorge on chocolates etc, we can eat a perfectly normal diet, including bread, butter and cheese etc, puds and cakes on the other five days which, somehow makes diet days easier.
I have been on and off diets all my adult life but find the 5:2 by far the best, both for losing weight and for maintenance.
I guess, if we start to put weight on again , we will cut our calories a bit on non fast days but, at present, even post Christmas, the 5:2 works for us. I wouldn’t risk cutting down to 6:1 though!!