I tried eating Primal back in July or August and had a really hard time with it and gave up after a day and a half because I felt so sick. I did research on marksdailyapple.com and found that I was probably eating so many calories from carbohydrates and very little from fat and protein, that going cold turkey on legumes and grains gave me the "low carb flu".
This time, I gradually decreased the grains and legumes over the course of two weeks then went cold turkey the rest of the way. I have been feeling great and am eating well. I have been pretty full due to eating mostly fat (nuts, olive oil, avocado, etc), then protein (mostly fish and pork so far), then fruits/vegetables to round out the day. I'm already losing weight and having no side effects. I will update with my weight later this week.