Have you ever done anything low carb before, @ladyandthechocolate ?
"Normal" Fast 800 is low carb, Keto is very (very) low carb and higher fats.
It can work faster in terms of weight loss, but the downside is you will most likely get side effects while your body gets used to it. It feels a bit like mild flu. It's even called keto flu 😆
A sensible thing to think about would be to buy some keto pee sticks from eBay for a couple of £ and then you can see how close to keto you get doing the normal Fast 800?
I am not doing strict keto. I have done before and I lose a lot fast, which is good for the morale. But it's too much for me 🙈
For me, normal Fast 800 and time restricted eating is my sweet spot. So I don't eat breakfast and stop eating before it gets too late on an evening.
Apologies if you have read/know all of this.