I have been more-or-less lowcarbing for almost 2 years. I work out 6 days a week (for about 10-12 hrs total per week). 3 days I run (between 4 and 6 miles each time at an average speed of about 7+ mph); 3 days I use my elliptical machine. I also take 4 weight classes and 2 step classes a week.

From my personal experience (others' may have different results) I ALWAYS have a fantastic workout the morning after a day in which I have eaten more than my usual amount of carbs. Any time that I have gone to induction-level carbs, I have found my workouts much more difficult - not impossible, but noticeably harder. If I stay at these low levels of carbs, my workouts improve over time, but they are never as good as when I am eating more carbs. I find that I need between 40-100 carbs a day to perform at my best.