It’s taken me 6 attempts at ironman distance *racing*, but i think that i have finally figured out what works for me. (Nausea has always been my nemesis during longer events, and i’ve tried all sorts of foods and supplements to fuel/combat it.) My solution, of course, may not work for you, but FWIW… I discovered after several years of trial and error that the only way to get through a long day of exercise was to stay away from seriously solid foods (mainly, energy bars in any form), and simple sugars as much as possible. I found that Hammer Gel products (no; i only WISH i were sponsored by them; i should be part owner of the company for all the revenue i’ve provided them these past few years!)
Hammer Gel, and their Sustained Energy drink mix (which depending on the strength you mix it provides mostly carbs, but a bit of protein as well, and is very mild in taste; you can actually ‘flavor’ it with a splash of your choice of Hammer Gel), and Endurolyte capsules (which saved me during Ultramax last year when it was in the 90′s, and down at the Buffalo Springs Half in Lubbock Texas in June) work perfectly. I had quite a long conversation with Steve Born, the founder of the company, at the Ultramax expo, who informed me that nausea and bloating during a long event or a long training session was often caused by the body’s inability to process the simple carbohydrates found in most energy gels and drinks.
In addition, the burst of energy you get from ingesting simple carbs is followed by real energy low. I know i sound like a commercial for Hammer Gel, but i can really tell the difference between their products (complex carbs) and say, GU or Clif shot, in terms of the ‘even burn’ of energy. I never really felt like i was out of gas during my last Ultramax, and didn’t have the nausea that i had in and after previous races (not to mention the medical tent experiences!). I had stashed my back up cans of ginger ale in my special needs bags and transition bags, but didn’t need them at all this go round. The only other thing i ate during the event was a banana midway through the run.