Hi Pearsoy,

I haven’t read Dr Mosley’s new book yet, but I understand he suggests to do the 800 a day for as long as it seems sustainable, and then to go to 5:2. In his blood sugar diet, for people with pre-diabetes, he recommended doing 800 a day for 8 weeks.

I’d suggest you try it for 2 weeks and then reassess. The important thing is to make it sustainable, so you don’t just give up and put weight back on again.

Even if after 2 days you can’t do another one, it is still okay, you can go to 5:2 and keep losing weight.

Wishing you the best of luck.

Pearsoy, I agree that taking it day by day is the way to start.

If you find you can handle 800 calories daily for a few weeks at a time you can also consider doing this in stages. What I mean is a period of weeks on 800cal, then 5:2 for a few weeks, then back to 800cal again. You can move between both options for as long or short a period as you like. 5:2 is quite easy, 800cal daily is much more restricted, but it will give you much faster weight reduction and also a faster improvement in health issues related to obesity. Only you can balance those things to best suit you.

Dr Mosley recommends up to 8 weeks on 800 calories per day then switching to intermittent fasting on several days per week.

He also recommends following a Mediterranean style diet and going low carb plus time restricted eating limiting the hours of the day in which you can eat and suggests aiming for 16:8 ie fast for16 and eat for 8 by starting with a longer eating period and gradually decreasing it.

If you’ve not fasted before all of this is going to take a while to get used to so trying it for 2 weeks is a good way to start.
I would suggest you buy the book if this is the first time you’ve tried anything like this.

Good luck.