I read a lot of people saying you shouldn't fuel with sugary/high GI (Glycaemic Index)1 foods, as you'll get a blood sugar spike, an insulin release to cope with it, and then a subsequent blood sugar crash afterwards that will leave you feeling crap and with little energy. I can understand this if you're just sat on a sofa doing nothing, but have there been any studies monitoring blood sugar in cyclists/athletes as they take in something like energy drinks and exercise at medium-high intensity?
The body can apparently absorb 60-90g of carbs an hour - is there a problem with taking on that amount of carbs in one go (e.g. a common combination of maltodextrin/glucose/fructose) and then cycling for an hour, rather than spreading it over an hour?
I've tried riding with low GI foods and they just didn't seem to give me enough oomph, maybe okay for relaxed touring but I tend to like making progress even if I'm not racing. The boost from an energy drink or handful of dates doesn't last too long, granted, but I can definitely feel it when it's there.
Footnote 1: At rest, food with a high GI will be converted into sugar quickly, which will raise blood sugar. White rice, white bread, energy gels, and similar foods have high GI. Fiber, fat, and protein lower the GI. The GI of pure glucose is 100, and foods are measured in relation to that. More information can be found on Wikipedia.