Definitely gels need to be in your 3-1-1 baggie if carrying on.
Powders....do not have to be declared. If you do not have room for the whole container of powdered mix, I have never had a problem with having powdered mixes (Accelerade, Gatorade, Carbopro) in baggies that I have labeled by hand. That is not to say that my luggage has never been inspected, but they have never taken any of that away from me, and I travel by air often to races. Couldn't even say if the bags of powder triggered the extra inspection, or other stuff I was carrying (bike tools, TP massage roller, etc).
I would recommend double bagging any powder, as it will make a fine mess if the bag gets a little hole or the seal comes undone.