So for today's QOTD: How did you figure out you needed some nutrition on longer runs? Advice from others, self-learning from bonking, etc? Did you do much testing of different types of nutrition? Gu/other Gels/sports bean/liquid?
My first race in October 2012 was a marathon. I had read on the internet to train with what the course was providing. So I went out and bought some tubs of Powerbar powder. Trained with it for the few weeks leading up to the race, and then used it on the course. They diluted it far more on the course then I was in training, so I got far less from it. So then I moved to finding my own sources to carry.
I tried carrying Powerbar powder in conicals and mixing my own liquid nutrition on course. I was wearing a running belt with 4 10oz bottles. But mixing while running ended up not being that easy and super messy.
Then I tried to do just water in the bottles and use gels instead. I tried a few varieties and based on a suggestion from McFlurry John I went with E-gel. That product seemed to check all the boxes for me. Multiple carb source. High carb content per packet. Included a sufficient amount of electrolytes.
Over the years I've tweaked the nutrition based on the research I've read. And later based on several sources of research developed a calculator that helps determine carb consumption rates both for loading and in-race. The calculator uses gender, weight, current estimated VO2max, goal pace, and normal caloric intake to calculate some recommendations. The data on men's vs women's needs for pre-race carb loading was fascinating. The calculator is certainly not a one size fits all, but more of a general idea recommendation. It's a good starting place to work from and then test in training whether you need more or less.
Right now, I use the Western Australia Carb loading procedure in the days prior to the marathon. I've used E-Fuel and Maurten for that. Maurten's dilution was 4.7 g carb/oz whereas E-Fuel was 2.0 g carb/oz which put the liquid burden of Maurten far less for the same carb content. But after completing the protocol several times over the years, my newest concern is whether the sheer volume of liquid consumed is diluting out my electrolyte balance in the day prior. So I'm testing out SIS Beta Fuel this time around as my carb loading product. Also a 4.7g carb/oz like Maurten, but SIS Beta Fuel contains Na, K, Mg, and Ca (where Maurten only has Na). Then I'm planning on drinking liquid IV in the days proceeding/morning of the races to make sure my electrolyte balance stays in tact. Then, I'll take 17oz of SIS Beta Fuel about 10-15 min prior to the race start. Then, I've been playing around with a super concentrated form of Tailwind at 1 scoop per 1 oz to dramatically increase my electrolyte intake while racing but minimizing the bulk of carrying something. I'll balance the Tailwind with my tried and true E-gels. I haven't actually followed through with this strategy yet, but I plan to start practicing it on all my long runs over 110 minutes.
I think I started out with Shot Blocks or the Gatorade Chews. I’ve used sport beans and Gu gels and peanut butter pretzels and Honeystinger chews and Waffles. I think I’ve tried a lot of things and for the most part nothing has seemed to cause a problem. I pretty much stick to Gu Chews and Endurolyte Extremes right now, but I’m always open to trying something new. Per my 
