In my opinion you should first try the 5:2 diet program because it is somewhat similar and based on actual scientific evidence. It is also much easier to follow along than the Three Day Diet.
Why? Well, let me warn you right away that the “Three Day Diet” is a very strict dieting plan and not everyone can follow it. However, if you can make it through the first week you're probably good to go. Still, this is hardly an effective long-term diet strategy and this is why I am against it.
If you follow the meal plan as expected then I am almost positive that you can expect to see some effective weight-loss. However, I strongly encourage that you do this in addition to a good exercise routine if you want to see real results.
Let me also include a word or two about the health effects of this program. While is completely safe and healthy for your body, it is a bad program for a long-term diet. After three-four weeks you should abandon this plan and switch to something sustainable to prevent the lost weight from coming back. So, let’s get in the details and the mechanics of the dieting plan. As you might have guessed by now the principle idea is that you will diet for three days and then eat regularly, in moderation, for the rest of the week.
Allow me to give you a simple example: you can use this diet program on the weekends and Monday (that's your 3 days) and then try to enjoy the rest of the word week as you wish. On the weekend you will rinse and repeat of course! However, during the rest of the week you'll have to make sure not to eat any junk food, unprocessed sugars and overall high calorie meals. I would personally like to recommend that you stick to the simple and easy-to-follow Mediterranean diet plan for the rest of the week.
So, let's look at the three day diet menu, shall we?