I've got CFIDS with all the trimmings.
When I started out, my exercise for the day was getting to the bathroom and back in the morning, and then to the kitchen and back in the afternoon. I'm not exagerating. You can imagine desperately having to go to the bathroom, which is only about ten feet away, and taking an hour or so to muster up the energy to get there. My major excursion for the week was to the corner store, about 500 yards away.

I too played around with "quick energy" foods, but that only meant added weight. The solution for me was to go with atkins.
I am still in bed most of the day and have to be very careful on what to spend energy on. I find that water and essential oils (flax etc.) make a big difference in taking and keeping weight off.

I stick to very low glycemic foods and make sure that any carbs are always accompanied with fat. Do not hoard your carbs for one meal. The idea is to eliminate the insulin rush. If you are exercising like a maniac (sorry bmeloche....meant in a complimentary way) then you can bend the rules and be fine. But if you are sedentary you might as well face reality.

Bye the way, over the past ten years I've had my ups and downs. I could do weight training for a while, but got hit with a major relapse that I am still recovering from. And when I have to energy to expand my activities, I also increase my carbs a bit. It is a balancing act, but it works.

Good luck

Colin