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The 10 Biggest Mistakes Endurance Athletes Make

#2: Simple Sugar Consumption

Thu, Jun  15, 2006 - By Steve Born

We believe that fructose, sucrose, glucose and other simple sugars (mono- and disaccharides) are poor carbohydrate sources for fueling your body during exercise. Also, for optimal general health, you should restrict your intake of these simple sugars (see Dr. Bill Misner’s article “113 Ways Sugar Can Ruin Your Health” in the Knowledge section at

For endurance athletes, the primary problem with fuels containing simple sugars is that they must be mixed in weak 6-8% solutions in order to match body fluid osmolality and thus be digested with any efficiency. Unfortunately, solutions mixed and consumed at this concentration only provide about 100 calories per hour, totally inadequate for maintaining energy production on an hourly basis. Using a 6-8% solution to obtain adequate calories means your fluid intake becomes so high to cause discomfort, bloating, and possibly oversupplying your body to the point of fluid intoxication.

You can’t make a “double or triple strength” mixture from a simple sugar-based carbohydrate fuel in the hopes of obtaining adequate calories because the concentration of that mixture, now far beyond the 6-8% mark, will remain in your stomach until sufficiently diluted, which may cause substantial stomach distress. You can drink more fluids in the hopes of “self diluting” the overly concentrated mixture, but remember that you’ll increase the risk of over-hydration. However, if you don’t dilute with more water and electrolytes, your body will recruit these from other areas that critically need them and divert them to the digestive system to deal with the concentrated simple sugar mix. This can result in a variety of stomach-related distresses, not to mention increased cramping potential.

Simply put, simple sugar-based drinks or gels have to be mixed and consumed at very dilute calorically weak concentrations in order to be digested with any efficiency.  A simple sugar-based product used at a properly mixed concentration cannot provide adequate calories to sustain energy production. Any way you look at it, fuels containing simple sugars are an inefficient, inappropriate way to fuel your body during prolonged exercise.

Complex carbohydrates (polysaccharides) are the wisest choice for endurance athletes, as they allow your digestive system to rapidly and efficiently process a greater volume of calories, providing steady energy. Unlike simple sugars, which match body fluid osmolality at 6-8% solutions, complex carbohydrates match body fluid osmolality at substantially more concentrated 15-18% solutions. Even at this seemingly high concentration, complex carbohydrates (such as maltodextrins and glucose polymers) will empty the stomach at the same efficient rate as normal body fluids and provide up to three times more energy than simple sugar mixtures, which means you can fulfill your caloric requirements without running the risk of over-hydration or a variety of stomach related maladies.
Recommendation: To get the proper amount of easily digested calories, rely on fuels that use complex carbohydrates (maltodextrins or glucose polymers) only, with no added simple sugar as their carbohydrate source. Hammer Gel and HEED are ideal for workouts and races of up to two hours. For longer workouts and races, select Perpetuem or Sustained Energy as your primary fuel choice.

Next time, Mistake #3: Improper Amounts of Calories