In the day to day I practice low carb eating and have been riding every day at moderate intensity and have had not had any issues, when I crank it up I like to make my own power bars with oatmeal, nut butter, raw nuts, and a small amount of honey. These have less sugar than commercial products, the honey is better for you, and it has a nice macro profile with the distribution of fats, protein, and carbs.
I have tossed these to fellow riders on longer trips and they describe them as being rocket fuel... it gives a quick boost from the simple sugars in the honey, the oatmeal has a longer burn time, and then you have some protein and fats in reserve.
The kids still have trouble keeping up with me on longer rides.