This right here: CRITICAL. Seriously, a more crucial aspect of this (or any other super-restrictive, insane diet) is hyper-crucial. When you decide to you might like to do the GSD, personally I think you need to read Get Unshredded first. 3 times. Then read it again the day before you start GSD.
And after you're done getting Unshredded, you NEED something like Precision Nutrition, http://www.precisionnutrition.com/products/system
or even something simpler like the diet plan outlined in Waterbury's Body of FIRE (which is really just PN for dummies in a way. Or, at least, a paint-by-numbers PN plan) follow it for 4-8weeks while you're reading PN and learning all the shit that will keep you from getting fat again.
All of this is stuff I wish I'D learned before I crashed and burned coming off a super restrictive diet. Had a read Get Unshredded first, I would have known what was happening to me, known what to expect in the first place, and known more about how to cope with it. Instead I popped back up 45lbs in a matter of weeks.
When Berardi goes into this part: "I wanted nothing more than a bowl of cereal for breakfast. Well, that bowl became a box. And that box, another. Three boxes of cereal and one gallon of milk later, I was lying on the floor in a carb-induced coma.
The weird part is that I wanted to stop at one bowl. Then at one box. But I couldn't. I was really hungry and didn't have a plan. And once I started eating and the insulin kicked up, I couldn't stop thinking about the next bowl. I was literally obsessed with eating more..."
It's no joke. It can't be stressed enough.
For me, it started with giving myself a treat I'd earned after reaching my final goal. One of those Starbucks cheese-filled pumpkin muffins they start selling in October every year. That opened the floodgates to waver afterwave of cravings for ice cream, cookies, pie, cheesecake, you name it... The sweet tooth hounds sprung from the gate and tore into me with overwhelming ferocity. I was so unprepared. And confused. I'd NEVER had a sweet tooth. Ever! I was the salty, savory carb-craver in the past. Why wasn't I at least craving potato chips, pizza, subs, burritos and lasagna? It made no sense! (actually, that part sweet vs savory STILL doesn't make a heck of a lot of sense to me. None of my old carb standbys appeal to me now. Pizza? Chips? Blech. I get kind of ill if I even try to eat them. The smell of them makes me queasy. But sit a cake or pie in front of me and I have to dial up the self control in a big damned hurry).
Anyway... I'm not the right person to talk anyone down from a restrictive diet like GSD, because I've gone even farther over the edge. It works. It can fuck you up, but you'll see results.
Just please know and understand what you're in for when you come off of it.