That's what people who don't need to diet, always say. I can assure you that even with vast reserves of will power and common sense, some people's bodies resist losing weight, it's not all about calorie intake. Often, it's about finding the right diet for you. I eventually discovered that I wasn't consuming enough calories, even on sensible well-known diet plans. Low carb, high fat works for me - it certainly doesn't work for, or appeal to, everyone. I am not, and never have been, a couch potato either, so please don't jump to conclusions.
As for this diet plan, It wouldn't appeal to me and I think it's a hard regime to follow for months. However, it's what many of the rich and famous do and many like to emulate them by copying beauty regimes, exercise plans etc., this is no different. My only gripe, apart from the expense is that it isn't the Lifestyle change needed to lose weight and keep it off, but it's handy for people who want all the thinking done for them.