I'm going to take the high road, not debate an asston of pubmed articles, and give you this link:
http://www.ironaddicts.com/forums/forumdisplay.php?f=46
Its a forum full of much more informed and experienced people than all of us put together - they'll be able to answer your questions.
The problem with pubmed is that yes, its all fine and dandy to read to conclusions drawn from specifically controlled studies - but that is not a substitute for tried-and-true practical advice from someone who has trained hundreds of people. It drives me fucking bananas when I see people say shit like this:
"
http://www.ncbi.nlm.nih.gov/pubmed/10204826
research published in 1999 found that when men and women followed a 12 week diet consisting of only 800 calories and only 80 grams of protein per day, they were able to maintain their muscle mass as long as they were exercising with weights three times per week."
and extrapolate that to insinuate everybody can maintain their LBM on an 800 calorie diet. Oh yeah? How much LBM did they have? How did their lifting performance get affected? Yeah you can eat at a deficit to burn fat and maintain LBM, but waving this study around is a bit misleading.
Bottom line, ask people who know what they're talking about (not me, not not_a_virus, not anyone here). Reading articles from pubmed is great but is no substitute for asking people who do this kind of thing for a living.
Seriously, just sign up for ironaddicts - this is the wrong place to ask