They do work. Thras looks like he was on a form of Protein Sparing Modified Fast. They work really well. I've done the same thing. The tough part about these diets is transitioning out of the diet, but if you follow the "maintenance" modes that most of these diets advocate, you'll be absolutely fine. The promoters of these diets do not advocate these as long term solutions. For people that are > 30% body fat, the longest recommended time to stay on this diet is about 12 weeks before moving to maintenance. For someone whose body fat percentage is less than 30 but greater than 20, the longest recommended time to stay on the diet is 2 to 6 weeks before, again, moving to maintenance. After two weeks on maintenance but not yet reaching the target weight, the person may choose to proceed with the diet or opt for a more moderate one.
Checkout http://bodyrecomposition.com which promotes a form of Protein Sparing Modified Fast that the author has dubbed "Rapid Fat Loss". He is not an advocate of protein shakes on this diet but rather obtaining macronutrients from actual food, because protein shakes are metabolized so quickly that the body feels hungry soon afterward.
Checkout http://bodyrecomposition.com which promotes a form of Protein Sparing Modified Fast that the author has dubbed "Rapid Fat Loss". He is not an advocate of protein shakes on this diet but rather obtaining macronutrients from actual food, because protein shakes are metabolized so quickly that the body feels hungry soon afterward.