One of those diets, Dr. Siegal's Cookie Diet, has been around since the 1970s. His website touts a "secret amino acid protein blend" as the vehicle for weight loss.
This recent N.Y. Times article examined these diets and their claims. The theory behind these diets is that high-protein foods curb hunger. Yet, according to the Times, none of these cookie diets is supported by a clinical study. No surprise there.