“While Paleo, high-fat and periodized diets have little or no effect on enhancing one’s endurance, there is a less risky tweak you can implement in your training to improve your ability to burn fat for fuel—regular rides on water. I began to implement them back in 2007, and at first I could scarcely go for one-and-a-half hours before I bonked. But as my body adapted, I was able to ride three, four or five hours on water alone. This approach has a big effect in activating the genes that stimulate the production of enzymes involved in fat oxidation, as shown in a 2005 study by L.J Cluberton et al.
If you decide to implement these water-only rides in your training, remember that these rides are depletion sessions, which leave you drained, and should always be followed by recovery days.”
Depleted and craving carbs in my case!