you have a link to a quick and dirty version of the RFLD. that is one i've never heard of before. Does it work with existing weight programming or is it like UD in that aspect?
Figured I'll just write few points up.. But if you want to do it I think you should read the book so you don't make any mistakes. It's extremely important to do things just as Lyle tells you to do. Otherwise things will go badly.
-Calories depend on your weight/BF% but it's very low. ~1000 kcal or so for most men probably.
-Very high protein, basically chicken breast or something similar 90% of time
-No added carbs (just what little you get from green veggies)
-Only fat source is little EFA so you don't drop dead
-Multivitamin, magnesium supplementation etc...
-Training should be scaled way down. Full body 2x week or 3x week Upper/Lower Split
-Very little cardio, preferably not at all in most cases
-Absolutely no HIIT of any kind
-Refeed once a week or not depending on your BF%
-Few "free meals" per week or not depending on your BF%
-Length can be 11 days or six weeks depending on your BF%
All in all it's not a nice diet but it's very effective. First few days are rough but after that it's easy to maintain. Comes without saying that if you don't know what you are doing or are prone to binging/yo-yoing you shouldn't even try this.
If you do it right you won't lose muscle even though it would seem like it.