A lot of runners love hard data--myself included. We like to know how fast, how slow, how light, how strong our runs and our bodies can be. GPS watches, scales, and other measuring tools have made it really easy to focus on the numbers instead of hearing the symphony of feedback that our body has been playing to us all along.
The same is true with nutrition. Too many runners are looking outside of ourselves for the perfect diet--judging ourselves and each other for whatever trends we are or aren't trying.
The truth is that the diets required to fuel our training can and should vary as widely as all the paces, lifestyles and body types you see out there running the race. For example, a 120lb East African training 150 miles per week to finish under 2:05 will have totally different fueling requirements from a 65-year-old American training her heart out to break 5 hours.
So, without judgement, here is what has worked in my career as a professional marathoner: