On fast days calorie intake is 400-500 k Cal. for women, 500-600 for men.
That's 25% of normal daily energy on fast days, a normal day would be 100%. What apparently happens is that ADF practitioners tend to eat ~110% on feed days. So their average daily intake is ~67.5%.
You can buy body composition scales, that measure many things including resting metabolism rate, visceral fat, body fat%, etc.
If I've understood things properly, resting metabolism rate is the calorific intake that one needs to maintain a stable weight (not allowing for physical exertion). Reducing one's intake below this means one should lose weight.
It would be a good idea to get organised and work out recipes and combinations that meet the RDA of protein and work-out your fast day eating plans, in advance.
My first fast day was unpleasant, but that was because I jumped-in without preparation or being organised. Fasting certainly gets easier.
According to the programme, the reason to restrict protein is to reduce IGF-1, which is implicated in the 'go' mode, cancers, cardio-vascular disease and diabetes.
Whereas excess calories are converted to fat.
I'm new to this. I've started on the ADF and intend to try it for six weeks, while monitoring the results. I might switch to the 5:2 regime for weight maintenance, it all depends on how things go, but I've already lost weight.
There seems to be so many potential advantages and I need to lose weight, that I feel convinced that unless I discover something bad that I will continue.