Probably my worst component of performance is nutrition. Some years ago it was a topic on this discussion group. If I recall, the thing to do was go for a 4:2:1 ratio of water, carbs, protein. A product called perpetuum was the thing and some preferred cytomax. I noticed improvement for workouts or races over an hour.
I've bonked under all conditions, even when I thought I was doing the right thing. My worst feeling is when I've taken excess water and no re-fuel. When I over hydrated I felt bad and had no go. When I underhydrated I could still push, but not as well and the recovery was worse.
One overriding thing: people are so wildly different that there is a problem with preachers. There are great paddlers who need very little water. Having somebody say “This is What Works” is a big red flag for me. I have given myself a dehydration injury - so I do need water. But I've over hydrated at less water than recommended by experts.
This is a huge component of performance and hope you kids out there are paying more attention than I did when I was your age. Here's some good non-promotional video (I highly recommend the first three):