I did the 5:2 diets a couple of years ago and lost a lot of weight. Don't try and do two consecutive days. A bit of advice , pick two days that you will not be at home, so you can't succumb, know exactly what and when you are going to eat on your fasting days, homemade vegetable soup is a life saver. I used to cut out breakfast, eat an apple around 12, vegetable soup as late as I can bear it, and then grilled/ steamed fish or chicken breast with a little bit of boiled rice. You will be so hungry anything will taste good. You will probably find on your normal days you won't each as much as normal either, so as not to undo what you did the day before ! Good luck. It does work .