@MikeHannigansStripyShirt well, I'm quite evangelical about fasting in general for it's numerous health benefits, but it a version of the 5:2 diet.
Instead of fasting two days per week, I do one normal day, then one fast day, normal, fast and so on.
On fast days I eat 500 calories or less, and I eat all of those calories in one meal at around 5pm. I built up to every other day fasting from three fast days per week. I love fasting, the weight falls off v fast, and especially fast at first, so it helps motivation, plus its easy (enough) to grit your teeth and endure the fast knowing the next day you can eat normally again.
After three fast days is suddenly very easy to fast, and you have so much more energy, especially on fast days. I also never get ill when I'm fasting, it seems to super charge my immune system.
Some people keep their calories below a certain amount on non fast days, personally I don't bother as I find the weight falls off fast enough without needing to. I do tend to eat fairly healthily, and follow a vaguely high protein low carb "dirty keto" diet.
I have been know to allocate all of my fast day calories to champagne and/or fudgesickles
but that's not recommended! It has never slowed my weight loss though.
So, after that time share hard sell, basically the fast day is tough for the first three fast days, but if you can grit your teeth through those you'll be fine. Plus you notice results from the very first fast day, which is a great incentive 