Level 8 Valued Member
Sluggish, carb-deprived trainees running on caffeine fumes and trying to perform high-rep Olympic lifts - this will not end well. In fact, this has been cited as one of the reasons for the high injury rate among CFers.
The short answer to your question is that you can probably survive near-daily metcons as long as you replenish your glycogen stores, i.e., eat more carbs. My understanding is that the athletes who compete in the Crossfit games eat as many carbs as they want. If you are feeling sluggish then you should definitely take note of what is going on with your body.
Shorting your carbs on a high octane workout regimen is just (stupid) misguided. That would be dogmatic 180° from where you want to be.