That load day will help, and even on days you are not eating a lot, if you can eat that 30 grams a couple of hours before exercise, it gives your body something to use for the exercise.
If you were only doing walking or slow running, low carb is somewhat manageable. But when you add the cardio and strength or resistance training, it pushes you into a different energy system.
If you haven’t read this one yet, this gives a bit of info on some of it:
the-3-energy-pathways