I'm not an athlete that engages in races or endures any kind of regimented training, but I do like to go for strenuous hikes on the weekend, and there's a mild bit of competition to hike fast and keep up as we power up 3000 feet of elevation.
I found the transition to be fairly difficult. It was rough for the first month, with some general weakness. I really slowed down on my hikes. Then it got significantly worse when my body finally released all the excess water it had stored and I totally crashed with electrolyte deficiencies. It took me a week to recover and feel about how I felt the weeks prior to that crash and I felt that way for months. Basically I felt fine with decent endurance but a reduced capacity for speed.
Slowly over the last few months I find myself feeling better and better until the last couple of weeks I have felt amazing. I felt so great this weekend I ran part of the way up the mountain. I had to wait for everyone at the summit. I haven't felt this good in a long long time. I haven't been first one up in a long time.
It has taken me about 4 months to make this much adjustment. I am not as low carb as I was at first, but I do believe the low carb transition helped me immensely. I have metabolic flexibility, the ability to exercise hard all day with minimal food. That alone is worth the price of the struggle to adapt. The slight increase in carbs over the last couple of weeks has probably helped me regain my speed, as has the strength exercises I have been doing for the past month. The strength exercises I KNOW have helped because I can feel all the new muscles being engaged.
Anyway, I hope my story gives you some insight to make a decision. If you choose not to go low carb, you can still choose to eat Primally. You'll probably have to consume a lot of rice, which is a fairly safe starch.
Female, 5'3", 49, Starting weight: 163lbs. Current weight: 135 (more or less).
Starting squat: 45lbs. Current squat: 170 x 3. Current Deadlift: 220 x 3