Kate: What Mama said. Sometimes the fat goes and water is retained. Just stick with it and you will probably get a whoosh effect when you least expect it.

Lakemouse: It's your preference. I weigh everyday and compare Saturday to Saturday. Some only weigh once a week, once a month or not at all. Fluctuations on 5:2 are very normal, so focus on the longer term trend than on the day to day ups and downs. And measure...sometimes the scale doesn't, but the tape measure shows other changes in your body.

To the Newbies ;-)

Here is my weightloss chart in 2013-2014 on 5:2. You can see it is a 'bumpy' ride. Some people lose linearly, but I think most don't.

As I gain 1-3lb of water over the weekend (mostly water retention) and lose this on my Monday fast. Over the course of a week my weight can fluctuate 4lb on maintainance. During weightloss I had 1-2 weeks with good losses and then 1-3 weeks with gains and maintainance even when strictly sticking to cals on fast and NFD. Lots can effect weightloss and water retention....hormonal cycle, sodium to potassium ratio of food, lost fat gets replaced with water in the cells first. On the scale you see the weightloss when the water is flushed out. So DRINK water and eat potassium rich foods.

It's just the body and how it works. Instead of getting too discourged, I started linking fluctuations to the food I had eaten. An example...If I eat grains I retain water, if I eat potatos, I flush it out. So after pizza or pasta (even within my cals) I gain 2-3lb overnight. If I fast, eat potatos or lots of veggies (water and potassium in there), that kilo disappears as quickly as it came.

So my suggestion is, get to know how your body ticks and you'll know how the scale will react before you get on 8 times out of 10. It'll still surprise you once in a while to keep you on your toes