I have tried fasting a little bit, not with great success. It started back in 2013, when 5:2 had its craze - in Denmark anyway. I think I have managed 3 times 36 hours, and that was it. I never got to a point where I felt good, I got headaches and felt dizzy, and was basically a bit of a lumb most of the day. So it does not feel productive.

Now that I am doing a medical trial I am actually getting interested in fasting again. I have to fast for 15 hours, and for 21 hours all I get to eat is a bowl of soup and a bit of bread and fruit. All to follow the rules of this study. I think it just might qualify as proper fasting. I am very hungry at least :)
In the beginning, I got the same "symptoms" and felt really poorly the first two days, but then I actually started feeling much better, both in body and mind. So I am sensing that it is just something the body needs to get used to, and I might just give 36 hours fasting another try! :)

Besides the "slumb", I think the hardest/weirdest part for me was the time of day when I would start cooking dinner... All of a sudden this anchor of the day was gone :) What to do with all that extra time!?