With regard to weight lose, gain, or maintenance, a calorie is a calorie. If you eat at a deficit you will lose weight and if you overeat you will gain weight. It does not matter what the composition of those calories are. The only benefits I see from going primal ( strictly from a weight loss perspective. I am not talking about any other health benefits) are :
1)Increased satiety, so you are more likely to naturally eat less
2)More of the weight that you lose comes from fat instead of muscle. This preservation of lean mass can probably be accomplished by lifting weights while being in a calorie deficit without going primal.
I looked at Mark’s pyramid How to Succeed with the Primal Blueprint | Mark's Daily Apple and he says that if you eat over 150 g of carbs per day you will likely gain weight. If you are counting calories and eating at a deficit, how can you possibly gain weight even if 100% of your calories come from carbs? There are plenty of people following conventional eating plans who are maintaining healthy weights or losing weight. I think mark’s approach is interesting and useful for people who have a lot of trouble with hunger while dieting. But, if you can eat at a deficit without going primal, what weight loss benefit does primal eating give you? Let’s say you have 2 twins who are the same weight and gender and are fed the same amount of calories and exercise the same exact amount. If you feed 1 a high carb diet and the other a low carb (primal) diet, they will both lose the same amount of weight.
I don’t mean to disrespect Mark or anyone else who supports him. I just want to see if I am missing something here.