I'm Yves.

The Fast 800 is not a good plan. It promotes consuming 800 calories a day, which is obviously significantly less than the bare minimum of 1200 calories/day for sedentary women. It is very difficult to get enough nutrients like calcium, protein, and magnesium on a calorie level less than 1200. Other problems often include negative energy balance, disruption of the menstrual cycle, and low bone density.

Try this instead. Easy to follow and sustain in the long term: https://community.myfitnesspal.com/en/discussion/1080242/a-guide-to-get-you-started-on-your-path-to-sexypants/p1