It really is very simple! These are the ‘rules’ of the 5:2 Diet/The Fast Diet. There are only two and they make it really flexible.

• You fast two days a week, ideally non-consecutive days are easier for most but you can do consecutive days if necessary.
• A fasting day is this: wake up, consume no more than your calorie allowance (600 calories for men/500 calories for women), go to sleep. Wake up and eat as normal the next day.

Yes, that’s it! The rest is up to you.

This is the ultimate in flexible diets – after all, a diet should fit around you and not the other way around! So, you can pick and choose your days each week based around social or work commitments as needed. If you prefer you can choose two days and stick to them each week, just swapping things around if other events crop up.

As for how to spend your calorie allowance, well that’s up to you as well! Some prefer to split it into several smaller meals, The Fast Diet book recommends having a breakfast and dinner but many of us at the forum have found that as soon as we eat we just feel more hungry and instead have opted to save the majority of our calories for a nice big dinner. You can eat well on a 500-600 calorie dinner! Plenty of non-starchy veg are ideal with a nice side of low calorie, low fat protein such as chicken, lean ham, fish or egg. I’ve written a post about what to eat on your fasting days too, you can find it here.

Remember that you do not have to consume the entire calorie allowance if you prefer not to. Sometimes I make a huge salad for around 250 calories and that’s more than enough to fill me up and keep me going. Some people prefer to stick to liquids only on their fast days, although the number of calories will depend on the liquid. I wouldn’t recommend a liquid only fast for beginners!

Some of us prefer to start our fast after dinner the night before our fasting day, but this is by no means mandatory or essential. It may save you a few calories over the course of the week and get you out of those bad habits of evening snacking though.

So, a typical 5:2 fasting day lasts around 36 hours – from dinner the night before until breakfast the day after.

2pm-2pm Fasting – a 24 hour fast?

There has been some confusion over the duration of the fast as technically it is only one day, but this does not mean it is only 24 hours – there is a sleep either side of the fasting day, making it nearer 36 hours. In The Fast Diet book Mimi Spencer mentions a 2pm-2pm “24 hour fast” as an alternative however this is rather confusing and somewhat misleading as those who have tried to fast with this method have found the weight loss to be minimal. The problem seems to be that with this method the calorie deficit is reduced as most would have a lunch before starting their fast, then fast through until a late lunch the next day. This in effect replaces only a dinner and breakfast with 500 calories of food rather than a whole day’s worth. If you are going to try the 24 hour/”1 sleep” method be advised that the weight loss will be slower than with the original method unless you remember not to have two lunches! Ideally you should have lunch, do your 24 hour of fasting and then not eat a meal again until dinner time (I suppose you can get away with a healthy afternoon snack to break your fast).