Between this and generally trying to lose weight I've been attempting to eat less, but I also find that it tends to make me lethargic and inclined to go to bed

Between this and generally trying to lose weight I've been attempting to eat less, but I also find that it tends to make me lethargic and inclined to go to bed earlier. I hope I can find a middle ground between reducing calories but still being able to do as much as I want to in a day.