Can anyone recommend something I can take for workouts?

I am on a long term cut with under 100g of carbs a day eaten before 1pm, I can do cardio fine at the gym but lifting weights is just beyond a nightmare at the moment, lethargic and my reps are 3-4 less than normal.

I just can never sleep on caffeine any more and my immunity to it is very high, is there anything else than can give a surge of energy?