I succesfully followed 5:2 in my early 30s keeping my weight around 11st (I'm 5"8). I then stopped and my weight crept up to 12st10 just before I became pregnant at 36 years old. I had hyperemesis that turned into nausea for the remaining pregnancy and the only thing to control it was eating extremely frequently (and taking cyclyzine), so I put a lot of weight on during pregnancy. I EBF and extended breastfed DD and could not shift the weight even gaining some more. DD is almost weaned now at 2.7 years.
I'm now 15st 5 
. But more worryingly my Fasting blood glucose is 5.6 (I have access to testing kit at work). This has really shocked me and I desperately need to do something about it and stick to it. From what I'm reading 5.6 is the bottom of the range for prediabetes and this is really concerning.
So I am trying both 5:2 and 16:8 (although tends to be more 18:6), and trying to reduce carbs, but not as much as I should.
Has anyone else monitored there blood sugars whilst fasting? How long did it take to see them come down? Did you notice the weight coming off easier once the fasting glucose level was in the normal range?