I can only speak for SB.
I did it the first time EXACTLY the way the book says(notice I said "first time"). Got the H/A, lethargy(tough to run the first couple of weeks) and I was irritable at times too.
HOWEVER..., NOW I've really stuck to working out 5-6x a week alternating either running or a Cathe cardio workout with a weightlifting workout(upper body)or allover weightlifting workout(I did Push Pull tonite)and just eating cleaner--I've got the Naples, FL 1/2 marathon in January--anyone else running it?)
IMO, SB is about healthy eating, not processed eating. You may cook a bit more than usual, but I tweak it for what works for me. The book is a good reference guide, but if you find yourself really "working" to change your way of "eating"--which may happen to eat "cleaner" anyway, the ability to stick with it is harder.
That being said, I have more definition than when I was on the Cathe trip, I'm more focused on cutting out some of the body fat than losing weight(which may happen but I'm not focused on the scale).
I can tell a difference in how I "feel" and as we all know, it took time to get the way we were, and it will take time to achieve the results you want. It's a combination of diet and exercise and with the Cathe workouts and cleaning up your eating habits(even with a splurge now and then)-you will see results, just be patient.
Just my 2 cents.
Mary
Formerly known as Luv2run