I found that if u decrease the amount of carbs u are taking, then u feel less energetic and feel tired throughout the day. we not only use our carbs for workouts, we also use it in our daily life like ur brain. although decreasing the amount of carbs u have to consume is inevitable when u r on a cut, it is a good idea to keep ur carbs pretty high from the beginning of the cut and start decreasing it from there. personally i tried low carb diet for abt 1 week and i can feel my strength and energy decrease significantly. but after 1 week i guess my body adapted to this and now i dont feel lethargic as much compared to like 2 days after eating in a pretty low carb diet. all that to say, carbs are very important.