You've got much more to gain going primal than if you don't and just train by running. The current way you are doing it, eating noodles and pasta, you will have a hard time not out-eating your training. As you burn sugar faster, you will crave it more and more. You will feel the fatigue. The weight loss and fat burning from primal will lead to a big improvement. You didn't list your run workouts or your running background and the way you are training for the 1/2 might have to be tweaked a bit. Your carbs would come from sweet potatoes, regular potatoes, white rice, dark greens, fruits, etc. You will feel sluggish at first and might spend 3-weeks or more switching over, but it is worth it. When you start feeling and sleeping better, you will know it was the right decision. My training switched from tempo and medium distance runs to sprint intervals 2x per week and 4-5 easy runs per week. The longest easy run I do is 10-miles. I have PR'd at 5k, 10k and 1/2M this year. I've lost 20lbs. The recovery from run workouts is much easier.