It’s not JUST about the Carb % of your sport drink, or as simple as solid vs liquid calories.

Dear Dr. Stoddard,
I’m wondering if you can explain something to me so that it makes more sense.

Sports drinks of course are made with 4-7% carbohydrates for reasons of absorption and hydration. Is it true that adding more carbs will simply pull water into the higher concentration to dilute it, rather than keep water in your muscles where it is needed?

With this in mind (assuming you agree), how does FLY fit into this picture?

If you add eload FLY to your bottles you are essentially increasing the carbohydrate concentration of your “sports drink”. So, are you compromising hydration for calories?

Thanks for your view on this.

Dear Anne,

Great question…topical!

It’s the energy density in the stomach/intestines that is the key…not so much the carb % in the drink or other ingested stuff. So, if one ingests a 4% carb drink, but then ingests a gel, or bar, or eload FLY along with that, then the energy density in the gut will be higher than that initial drink of 4%. If all they ingest is a 4% drink, then yes, the energy density in the gut will be 160 Calories per litre of fluid. But if you now add anything else, the ED will rise accordingly.

So, does it make sense to say that a 4% drink is the way to go, and then get the rest of your carbs from a bar? Or, to add FLY to your drink? Or to just use water, sodium and gels?
Doesn’t really matter…because the final common pathway is the ED in the gut from all sources.

The higher the ED, the more likely a person will have troubles digesting and absorbing, and yes, the more likely there will be an osmolar effect sucking water into the gut.

The question is, how much can an individual tolerate? Drink research as suggested no more than a 8% solution, but that’s got it’s problems as it also depends on what carbs are in the solution i.e. we know fructose is irritating.

In the end, some people have to ingest more carbs than that to fuel their event, and if they can meet fluid/sodium needs AND ingest all of those carbs, then great. If not, the needs of water and sodium have to be met first, then layer on top the carb needs to the level the person needs and can tolerate.

As you know, e load endurance formula starts at 5.4%. Why? Only because I felt in designing it that this was a better starting point re energy density of the drink, vs the 6-8% found in other drinks. But, once you add in the other sources, energy density rises, whether it’s FLY, gels, bars,chews or whole food.

You may also find out article on “Tips to Keeping your Gut Steady at Ironman” very helpfull as well as How to carry eload on course events.

Douglas W. Stoddard MD, M Sport Med, Dip Sport Med, ES
Medical Director-Sports & Exercise Medicine Institute (SEMI)
Medical Director-e load Sport Nutrition