I am on my 12th week with the fast diet now.
I gained almost 25kg in a short time more than 10 years ago after working too much, eating too late and quitting exercise. Since then, I have applied my will power to get back to my ordinary weight, both by looking at my diet as well as exercising.
Weightwise it has gone up and down and I have found out that for me, losing 10kg on GI or VLCD does work, but in the end, I end up gaining at least the same amount. For the last five years I train 2-3 days per week for at least 5 hours. However, apart from the many benefits of training it doesn´t seem to affect my weight especially much. I do budo sports so it´s quite good allround exercise. I am well read on nutrition data and don´t overdo eating generally but that will in the end keep me at the same weight. But I do love good food and during weekends, we do some serious cooking.
I decided to test 5:2 for that reason. Can I sacrifice 2 days per weeks and keep eating anything I want the other days? Wine on a Tuesday if I want? Peanuts on a Thursday? Pizza for lunch? Etc.

I decided to “sacrifice” Mondays and Wednesdays and not think mind about what I eat the other days. That doesn´t mean a double whopper meal every day but it does mean normal food and definitely a burger or pizza for lunch now and then. Just to keep track for myself, I started to use a calorie counting app all days, but I don´t care if it´s 1500 or 3500 the non-fast days, it´s just for record keeping. I also weigh myself every morning and every evening for the same “statistics gathering” purpose. I want to see the correlation in the long run. The worst day for me to go up on the scale is on Monday morning so that´s my only interesting reference point on whether it works or not.

It works. It really does work.

I read a little on the forums about and saw a lot of questions on what to eat and if one could take a pint with friends etc. My own finding is that it works extremely well to carry on as usual with normal eating patterns, normal living. I steadily drop about 0,5kg per week pursuing this. I could probably lose more and quicker if I adjusted even more but the whole point is not doing so. As I constantly see that the trend curve is downwards even if the other days of the week have been high in calories, it boosts my resolve to continue.

To make it easy, I eat the same stuff every fast-day. A glass of gazpacho for breakfast at 100kcal, a can of weight watchers hot noodle soup for lunch at 100kcal and then a toast with chicken breast in cooking cream with some paprika or onions and a lot of spices for dinner at around 400kcal.

Michael Mosley, brilliant! Absolutely brilliant! Worthy of a Nobel Prize as it easily can make a huge difference.

12 weeks in and I can see myself continuing this without any problem. If a 2-day feels tough, there is always the promise of some very good food to be had the day after. That is so phsycologically important and what I belive makes this work. The positive side effects are an added bonus.