I've been training for triathlons while adhering to a ketogenic diet since October 2015. Initially I struggled. It definitely felt like a step back. Over time m

I've been training for triathlons while adhering to a ketogenic diet since October 2015. Initially I struggled. It definitely felt like a step back. Over time my body adapted and 3-4 months later I was performing on the same level without consuming copious amounts of carbs as prior to going keto. These days I can wake up from a 12-18 hour fast and run a marathon at an easy pace while ingesting zero carbs in the process. I ingest some carbs during actual races when glucose utilization is higher due to higher intensity. You will always need some glucose and the ratio of fat/glucose metabolism depends on intensity. Basically if you push the pedal to the metal your body will utilize what it has got. With that said, I feel like keto adaptation definitely broadened my options for how to pace myself and how to use my energy reserves during training and races.