http://en.wikipedia.org/wiki/Ketogenic_diet
http://en.wikipedia.org/wiki/Atkins_diet
High fat, low carb diets have been around since the 1920's, also known as Ketogenic Diets.
As exampled by the Atkins Diet Revolution, it has been said, most simply,
Dr. Eric Westman
, director of the Duke University's Lifestyle Medicine Clinic and co-author of "The New Atkins for a New You," believes low-carb or Atkins should be viable options among diets.
"The Atkins diet was labeled as a high-fat diet," Westman said in an interview with The New York Times. "We've been told over the past 40 years that fat in the diet is bad. Now we know that fat is not bad. What's happened is that there is a paradigm shift in thinking about carbohydrates, fat and protein and health."
-Wikipedia
This shift has had a marked effect on how diets have been perceived and have been a great bell-ringer for many people. It's an expensive diet, but if followed it has certainly shown results and not as expensive as Jenny Craig or other similar diet plans if you self-administer and can stay on track with it.