While there are general principles to follow, nutrition has to work for your individual needs as an athlete. For me personally, the Osmo active hydration works very well. Dr. Stacy Sims, founder of Osmo, is a big believer in using liquids to hydrate and real food/solids for calories. However, this idea of “solid” nutrition may not work for every athlete out there. Here’s a look at at an Ironman athlete who modified the Dr. Stacy Sims’ recommendations and experienced great success.
http://www.slowtwitch.com/Features/Osmo_Follow_Up_3874.html