Originally Posted by kf5nd
The energy gels make heavy use of high fructose corn syrup (HFCS), which has been implicated as a villain in the development of obesity and diabetes in our society.
Any problem with a cyclist using it as an energy gel, when the cyclist is eating 250 Cal/hr of HFCS, but is probably burning 2x or 3x that number of Cal/hr on the bike? My thought (hope?) is that the substance will be burned off so fast it won't hang around long enough to do any damage.
I suppose one could always suck on honey. Also, HFCS is getting more expensive as cars compete with humans for corn (corn-based ethanol).
Simple sugars (and other carbs) taken in with full glucose stores cause an insulin spike, which leads to the sugar being stored as fat, a drop in blood sugar, and hunger. Over time, it leads to insulin resistance and sometimes type 2 diabetes.
The story during exercise is very different. Taking in sugars keeps up the blood sugar, which is what you need to delay exhaustion. You don't get the down side because it's not excess sugar.
Food for fitness covers all of this.
Too much fructose may be an issue. Fructose absorption is slower than that of other sugars (it's believed that it operates by diffusion rather than by sodium-mediated transport, as glucose does). This means that it sticks around in the stomach longer, and if it's not absorbed fast enough, it can cause the dreaded "GI distress". Fructose is absorbed faster when in combination with other sugars, which is why many drinks use both.
There's also some evidence that a fair number of people don't absorb fructose as well as others.