What happens when you increase calories slightly but don't increase carbs.
Day 1 you eat 1200 cals with 50 grams of carbs
Day 2 you eat 1500 cals with 50 grams of carbs.
Do you feel worse on the high cal day even when keep carbs low?
I did strict keto for an entire year, carbs could foul up my body and make me lethargic. However I could increase calories by adding in more fat and it would make me more energetic.
Instead of cheating with carbs have some more fat. I bet you will feel much more energetic and your runs will improve.
Adding in more carbs during weak moments will just keep your body shifting and transitioning to different energy systems. Keep it running on fat by eating fat and keeping carbs low