I watched the Horizon programme with Dr Michael Mosley last year and was interested in the idea of fasting for weight loss and also fasting for health benefits. I listened to Dr Varady's interview on the programme with some interest as only her research was on actual people, who wanted to lose weight. Admittedly the studies were quite small, but they were sufficiently powered to show that weightless was possible in the long term with Modified fasting every other day.... (not 5:2). I also paid attention to the reasons that Dr Mosley gave for not wanting to do this (too hard... didn't really want to lose much weight..... looking for the other health benefits, more than the actual weight loss) and 5:2 was what worked for him personally... there is no research to back up the efficacy of the diet... just personal experience and anecdotal evidence (i.e.: the man next door lost 10lbs and I heard of a woman in the London losing a couple of stone doing 5:2) and some assumptions based on every other day fasting, Chronic calorie restriction and some studies on mice. I bought the 5:2 book last year and did it for 6 weeks... I lost NOTHING! .... Dr Krista Varady published a book this year with all her research in it... I'm impressed by the numbers.... 90% of weight loss is fat Vs 75% of weight loss being fat on conventional diets. Good evidence to support long term maintenance using alternate diet days (1000 cals instead of 500cals on fast days) a year of study showed average regain was around 2lbs which is acceptable in my world! The study also looked at how often people 'cheated' on diet days.... and found that on average cheating occurred 17% of the time, but importantly the STILL lost weight! I've done Cambridge diet with success in the past, but it's just so antisocial, not being able to eat with friends for weeks and weeks, that I thought that this would be a more acceptable lifestyle that total abstinence from food! I'm only 3 days (2 diet days) in and already I've lost 1.2kg! I'm absolutely delighted with this excellent start!! (the book also advocates daily weighing as a tool for success, and this is supported by research evidence) Planning on charting my success here as I have a lot to lose again!