The Straight Dope on Sugar in Sports Drinks

November 12, 2009    |    Matt Fitzgerald

Sugars such as sucrose and fructose are the main ingredients in most sports drinks. Despite the commonness of the use of sugar in sports drinks, there is a great deal of confusion among athletes regarding the effects of these ingredients, the optimal types and sugars in sports drinks, and so forth. Here’s the straight dope on sugar in sports drinks.

The Reputation of Sugar

First of all, sugar has a reputation as an unhealthy nutrient; consequently, there are those who believe that the use of sugar in sports drinks is bad. But sports drinks are formulated for a narrow use and to serve a specific function: to enhance exercise performance. Therefore, consuming the sugars in sports drinks could only be bad if they did not serve this function better than alternative ingredients, or if using sports drinks for their intended purpose caused major negative health problems that outweighed their performance benefits. But research has clearly demonstrated that the sugars in sports drinks enhance exercise performance significantly, and there is no evidence that consuming sports drinks exclusively within the exercise context causes weight gain and metabolic disorders, as general overconsumption of sugar is known to do.

Most endurance athletes understand that the sugars in sports drinks are beneficial, yet they are still affected by sugar’s negative reputation. Within this population, anti-sugar prejudice takes the form of a belief that certain fast-acting sugars in particular cause an energy spike followed by an energy crash that wreaks havoc on performance. According to this viewpoint, slower-acting sugars and non-sugar carbohydrates are better, because they provide a steady supply of energy that does not terminate in a crash.

Misguided Beliefs

These beliefs are completely misguided. In fact the human body is incapable of absorbing carbohydrate as quickly as carbohydrate is oxidized in the muscles during moderately intense to intense exercise. Thus, to get the maximum possible benefit from carbs consumed during exercise you want to consume the most rapidly absorbed and metabolized types of carbs possible. There is no advantage whatsoever in consuming carbs that take a long time to reach and be used by your muscles. To the contrary, relying on slower carbs will only exacerbate the unavoidable carbohydrate deficit that results from the differential rates at which carbs are burned and absorbed during exercise.

An excellent example is galactose, which is a slowly metabolized sugar that was once made the principle sugar in a sports drink made by a manufacturer that mistakenly believed that slow carbs are a good thing. But a study found that a sports drink containing the faster-acting sugars glucose and fructose enhanced cycling time trial performance significantly more than a galactose sports drink precisely because galactose takes so darn long to reach the muscles.

Also, the phenomenon of reactive hypoglycemia simply does not occur during exercise. No matter how much sugar of the fast-acting types you consume, you cannot and will not experience a rapid decline in blood glucose resulting from excessive insulin release, as is possible at rest. During intense exercise the only thing that will cause your blood glucose level to decrease is depleting your liver glycogen reserves, which will only happen faster if you fail to consume enough sugar or misguidedly consume “long-lasting complex carbohydrates for steady energy”.


Now, some complex carbohydrates, such as maltodextrin, do perform as well as simple sugars such as fructose, glucose and sucrose during exercise. But that’s because some complex carbs, including maltodextrin, are metabolized as quickly as most simple sugars are (just as some simple sugars, such as galactose, are metabolized as slowly as most complex carbs are).

While some types of carbohydrate are better than others, two carbohydrates of the right types are better than one. This is because each specific carbohydrate is absorbed and metabolized through a slightly different pathway than any other. Thus, when you consume any given carbohydrate at a rate that is sufficient to saturate that pathway’s capacity, your body is still able to absorb and metabolize other carbs through their distinct pathways. Consequently, when you consume two compatible carbs at a high rate your body can absorb and metabolize more total carbohydrate than it can when a single carbohydrate is consumed at the same high rate.

Can this make a practical difference to your performance? You bet.

A study by researchers from the University of Birmingham, England, showed that a multiple-sugar sports drink enhances performance in a race-like endurance effort more than a single-sugar sports drink. On three occasions, eight cyclists completed a two-hour glycogen depletion ride on a stationary bike followed immediately by a simulated time trial that took roughly one hour to complete. In one trial, subjects consumed plain water.  In a second trial, they consumed a glucose-only sports drink, and in a third trial, they consumed a glucose-fructose sports drink containing the same total concentration of carbohydrate as the other sports drink. On average, the subjects completed the glucose-fructose time trial 8 percent faster than the glucose-only trial and 19 percent faster than the water trial.

High Fructose Corn Syrup

One sugar that is used commonly in sports drinks—although less and less so—is high fructose corn syrup. This sugar has acquired a very bad reputation based on a little bit of science and a whole lot of media hype. In fact, there is nothing inherently bad about high fructose corn syrup. It is nothing more than a combination of what might be considered the two most natural sugars on earth: glucose, which is the sugar your body runs on, and fructose, which is the sugar in fruit.

Why does high fructose corn syrup have a bad reputation? Simply because our society is not quite intelligent enough to distinguish between food ingredients that are inherently unhealthy and nutrients that we simply consume too much of. For example, the average person believes that saturated fat is inherently unhealthy. But it is not. Our bodies use saturated fat in all kinds of important ways. But we happen to consume too much saturated fat, and that causes problems. It’s the same with high fructose corn syrup. The problem is not that this ingredient contributes to obesity and metabolic disease more than other sugars on a gram-for-gram basis. The problem is that the average American consumes 60 pounds of HFCS per year! Any type of sugar will make you fat in such volume!

With respect to sports drinks, it bears repeating that these products are not health foods. They are designed to enhance exercise performance, and research has clearly shown that HFCS is as effective as other sugars in this regard.

About the Author

Matt Fitzgerald

Matt Fitzgerald is a journalist, author, coach and runner specializing in the topics of health, fitness, nutrition, and endurance sports training (read more about Matt on his blog). Matt uses TrainingPeaks to train, coach and deliver pre-built training plans for runners including training plans built specifically to be used with a Garmin Forerunner. View Matt's plans here.

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