I had sort of built up to this.
I started out doing the Anti-Inflammatory diet, which is actually very similar to Primal in that it eliminates all grains, sugar, processed foods, etc. There are some variances- it allows legumes, disallows dairy, and disallows nightshades. But I lost 20 lbs in a month on that diet.
Later my doctor explained to me that I have a metabolic type that is very sensitive to carbs, and that I should limit carbs if I want to lose weight.
I kept stumbling across people having success eating Paleo/Primal and one day I found MDA. I spent most of that day reading MDA success stories and the concept behind the lifestyle and decided to try it. I am losing weight on the diet, but more importantly I feel GREAT eating this way. My energy levels are consistent, without the crash-and-burn I used to get when the carbs wore off. I still eat carbs, but not like I used to and they are all from whole foods now. I've found just following the 80% rule seems to work for me and if I want to cheat one day and have pasta I can, so long as the next day I get back on plan.
High Weight: 225
Weight at start of Primal: 189
Current Weight: 174
Goal Weight: 130
Primal Start Date: 11/26/2012