5:2

has anyone tried this? i have done just 2 weeks of the 5:2 diet which is essentially fasting @ 500 calories a day 2 days a week, plus tracking my food (i allow myself 1400 cal. a day) on the other 5 days of the week. It has given me great results, I think. I've lost about 3 or 4 lbs from fasting alone in the last few weeks, plus some more from my normal dieting and exercising. I would like to hear other success with 5:2 and any observations you have had when using it. Is it safe to work out on my fasting days? Is it ok to have my two fasting days back to back as opposed to alternating?