It is just a typical diet for losing weight quickly, i.e. a diet that provides only around 800 kcal/day, while providing normal quantities of proteins, essential fatty substances, vitamins and minerals, to avoid other health problems.
My impression is that the default recommendation from the literature is "Mediterranean diet with counseling from a certified nutritionist" and evidence of any other diet that works would help expand options for folks with pre-diabetes.
What I find interesting and different about this diet is that it's a total replacement of your existing diet. It doesn't involve calorie counting, food pyramids, or vague suggestions to eat "more vegetables", "healthy oils", or "less snacks".
I assume that you get a box in the mail with your food, marked for specific meals, and you can only eat what's in the box and nothing else. There is no deviation (unless you cheat) but no complaining about the cost of food or difficulty of preparation.
Also I expect the number of people who could follow this diet to be extremely low, but I also don't know how it would compare to the average dieting plan.
You need to restrict calorie intake significantly for 3 month period for metabolism to change for the desired result. Many people could not finish the program.
It is just a typical diet for losing weight quickly, i.e. a diet that provides only around 800 kcal/day, while providing normal quantities of proteins, essential fatty substances, vitamins and minerals, to avoid other health problems.