Maybe a hard boiled egg around that time or a little earlier so you don't get to that state? It's low carb, pretty portable and can be made ahead.
As far as supplements, I'm not recommending, but will tell you what I take that is working for me, a multivitamin call Alive Women's Energy, Nature's Way, there's been a lot in the news lately about vitamins so you have to decide what you want to do on that front.
There's a poster on the wall at work that says to take a 10 minute walk to increase your energy.
Best of luck to you