Not to make you go all unhealthy and do this diet the "wrong" way, but I just wanted share my experience with it... I did pretty much everything you're not supposed to do, and it worked fine, without any problems. I should also note that I'm just 19, so maybe it only worked fine and everything, because I'm young and I can get away with doing whatever I want? I don't know...
By doing pretty much everything you're not supposed to, I mean-
I was basically just living off high % protein whey shakes on some days (most days, to be honest) - on almost all days, at least 75g of protein was from whey shakes.
I was smoking weed everyday.
I didn't drink that much water, just the normal +- gallon a day, or just how much I felt like drinking.
I did sleep 6+ hours most of the days, but not on all days.
I didn't eat much veggies, I didn't take potassium or whatever is recommended, only thing I took was fish oil.
I didn't even eat the recommended amount of protein- I estimate my lbm at 160-170lbs, and often I ate just about 140g protein daily.
Most of the solid food I ate was either chicken breast/cottage cheese/canned tuna/cucumber.
I didn't do ANY (not even much walking) physical activity besides lifting weights, and it was 2 times a week at most, usually just once a week.
In the last few weeks, I basically switched to a protein shake diet only, using a 60% whey protein/25% carb powder, and again, weight loss was just fine, even though I was eating quite a few carbs at this point.
I didn't do a structured re-feed too many times, and it was pretty random if it happened... however I did have a free meal more times in one week than I was supposed to, on quite a few occasions - but I did keep these meals somehow normal, and I tried to make them "diet"-ish.
Not saying you should do it like I did, I'm sure I didn't do it optimally... but it still worked VERY well. I'm very consistent with logging my lifting, and besides my squat, non of my lifts went down much, even though I lost a solid 22lbs in about 8 weeks (by that I mean without water weight fluctuation). For example, my deadlift went from about 500 to 485, my overhead press went from 200 to 192,5. So I don't think I lost much lean body mass.
I think the safety precautions and whatever are bit overdone by Lyle in this book. My interpretation of this whole diet is - "eat as little as possible for the most weight loss, while getting in enough protein" ..at least 1g protein per pound of LBM is enough too imo, but you can't go wrong with more. The other stuff (potassium/whatever...) you do that for health reasons, hunger satiety, etc, but the point is that you eat protein to keep your muscles, and the caloric deficit causes the weight loss.
I, for some reason am very weird with food, and can eat a ton of it if I feel like it, or I can fast for a week, without any problems... I just get used to it in a matter of days.
Only problems I'd have is hunger before sleeping, which would not allow me to fall asleep. When you've also smoked some pot, it can be quite bad.... so in that case, I'd just eat some more cottage cheese, maybe some rice,and maybe have some bread with butter or something.
Definitely don't be afraid that if for some reason you eat say 150g protein/ 60g carbs/ 60g fat , that the dieting progress of that day is ruined, or will be much slower, and you'll lose muscle. The difference will be minimal from eating the recommended 200/20/20 or whatever it is.
Again, the whole thing is a bit overdone imo... the point is, that you eat enough protein to keep your muscles, and the less you eat of the rest, the more weight you lose - so just eat as few calories as possible, while getting enough protein. If I were to do it again, I'd add oatmeal to the list of foods that I'd eat very often, and make up for eating it by adding some cardio.