I think it depends on your metabolism. My observation from hanging around these threads and runners (I am a runner) is that if you metabolize carbs well - meaning no high blood sugars, no hypo episodes, etc - eating more carbs will give you more energy for your workouts and help with recovery, blah blah. If you are low carbing due to a metabolic issue that leaves you slumpy when you eat carbs, the carbs will eat into your energy for running. Me and hubby are opposite - I can handle lots of carbs and he gets more energy from zero carb (both runners). I find I have been able to lose weight on over 100 carbs a day, but only combined with intermittent fasting.