Can someone provide a concrete example of what this diet is?
This is a diet produced by a group of researchers at USC led by a Dr. Longo that was used to try to avoid the effects of prolonged fasting (PF), by instead using a 5 day period once a month where nutrient intake was slashed by 34-54%.
Here is the summary from the publication in this June's "Cell Metabolism", that outlines the effects and benefits.
It grew out of yeast studies, where they noticed that independent of the yeasts actual life cycle, fasting produced longer life spans. When they expanded it to mice and humans, they found that IGF-1 (Insulin Growth Factor 1) was reduced. This is a hormone that helps promote aging, and is possibly linked to increased cancer susceptibility.
Since prolonged fasting (traditional, no food fasting) is hard for people to stick to, they came up with a reduced diet, with specific ratios of carbohydrates, proteins, fats and other nutrients.
However, they did stress that it is not something that should just be done without intervention, and also that if you are at or below a normal body weight, it probably shouldn't be done.
It's currently in review with the FDA to see if/how it can be introduced as a possible way to combat obesity, so I don't expect any books or other guidelines out on it any time soon.
There are websites such as this one that have created mimic plans, but they are not endorsed by, nor affiliated with Dr. Longo and the study group.