During the summer holidays I decided I wanted to loose some weight because many of my clothes didn't fit me any more. Obviously I had absolutely no idea where to begin until my friend told me about the 5:2 diet. This is where for 5 days you eat around 1500 calories worth of food and the other 2 days you would only be able to eat 500. Putting it straight out there I do not recommend using this diet to loose weight if you lack will power! I only managed it for 1 or 2 weeks and by then I'd realised there was more than likely a better way. Also on the days where I could only eat 500 calories I struggled to do anything because I did not have a sufficient amount of energy. Using the 5:2 diet stopped me from being able to eat vegetables and fruit on the days of 500 calories because some of them provided over half the calorie intake. Then of course I was open to 'the light', I began looking around seeing what I was eating that was bad and pushing it to one side. See with the 5:2 diet you'd still be able to eat really bad food that's either full of fat or sugar so the scales were bound to stay the same. I looked at my scales after about 2 weeks of the 5:2 diet and exercising and the number had barely dropped at all. But then when I began to eat fully healthily after about a week I could see the numbers dropping.
Overall I wouldn't really suggest using this diet plan unless you have strong will power! Otherwise go for the healthy option of fruit and veg and minimising the fat content in your diet!