The Straight Dope on Sugar in Sports Drinks

By 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.

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.

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."

Read more in the full article.

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Comments

[Ian Hamilton]

Hi- thanks very much for the article. So where on the specrum of "slow" to "fast" sugars does maltodextrin fit in? I've had the impression that it is a longer chain complex carbohydrate.

Also, is Xylitol a sugar in the metabolic sense?

Thanks!
Ian.

[Matt Fitzgerald]

Ian,

Maltodextrin is a complex carbohydrate that is absorbed and metabolized as quickly as most simple sugars. Many athletes (and sports drink makers) believe maltodextrin is good for use in sports drinks because it is not a complex carbohydrate. In fact, it is good because it is absorbed and metabolized quickly.

Matt

[Jim Wadleigh]

Holy cow! An intelligent article about nutrition. As a nutritionist who races, I am astounded by the acceptance of anecdotal, illogical and sometimes blatently commercial ideas as if they were proven. "My buddy says he read that if you eat "insert latest food fad here" before/after training, you'll "insert desired effect here". Good on you mate for thinking it through, using credible science and going against the street.

[Ken Sparrow]

Hi Matt, a very interesting article. Could you provide some citations of the studies you based it on?

Thanks

[Michael Burris]

Thanks for the article. I was joking with some training buddies over the weekend about how my go to energy drink is till good old Coca-Cola. Say what you will, but when I need a bump towards the end of a long ride, I drink a Coke and I always feel better.

Mike

[TW]

Please clarify: you say, "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.”
Yet, as a response to a question you say, "Maltodextrin is a complex carbohydrate that is absorbed and metabolized as quickly as most simple sugars. Many athletes (and sports drink makers) believe maltodextrin is good for use in sports drinks because it is not a complex carbohydrate. In fact, it is good because it is absorbed and metabolized quickly."
So is Maltodextrin a complex carb that will cause glycogen depletion?
I have never bonked using the complex carbohydrate - maltodextrin and as I understand will empty from stomach as fast as simple sugars at higher percentage solution. and glycogen itself is a "complex carb".
Thanks