Sugar for Sport
by GRP dietician Megan Chacosky
There are few words in the nutrition lexicon that conjure up quite as much reactivity or confusion as “sugar.” Sugar has more recently become a catch-all term, with primarily negative connotations, for any type or style of carbohydrate; however, sugar is in fact just one of the components of carbohydrate structures - in addition to starches and fibers - and is a crucially important component at that. The complexity of carbohydrate options, and the incredibly vital role they play in fueling our brain’s and body’s energy in and out of sport, aren’t done justice by discounting all sugar as “evil” or “poison,” as the media is often wont to do. Especially for athletes training and competing in any moderate- to high-intensity zones, learning how to utilize the different types of sugars within a fueling plan can be a performance-enhancing alliance.
Sugars are a type of carbohydrate that primarily serve all living things’ need for energy production, energy storage, and cellular structure. Sugar molecules are composed of differing balances of carbon, hydrogen, and oxygen atoms, in a multitude of molecular shapes, which determine their unique structure, purpose, dissolvability, and even taste. The basic chemical classifications of sugar are:
While very few people (I hope!) put the ingredients “glucose” or “sucrose” on their shopping lists, when prepping for an endurance outing, better understanding how these different classifications and individual types of sugars play a role in energy provision, energy storage, and gut digestibility might just be the next layer of unlocking more efficient training and racing. From the practically infinite details of molecular sugar ratios, portability and palatability, sport food products like electrolyte beverages, bars, gels, gummies, etc. have all been rigorously tested and intentionally designed to be used for the purpose of fueling before, during, and/or after a wide spectrum of physical activity; sugar has been repeatedly proven to be impactful and purposeful for enhanced sport performance. That being said, sugars are certainly not all created or utilized equally, and it’s perhaps worth over-clarifying that targeting these products for moments of intense or elongated performance serves a very different goal than regularly consuming high volumes of any type of sugar outside of a sport-oriented setting.
Within the world of endurance sports, however, the typical recommendations for carbohydrate intake range from as little as 30-60 grams/hour for slower paced athletes or events of ~60-120 minutes total duration, all the way up to 60-90 grams of carbohydrate each hour for elite athletes and/or events of much longer duration (e.g. 3-20+ hours). When it comes to figuring out how to meet those lofty carbohydrate recommendations, the main players in go-to training fuels - both natural and created - are glucose (also referred to as “dextrose”), fructose, sucrose, and maltodextrin. Some of the main take-aways to understand about these sugar sources:
Glucose, fructose, and sucrose are all naturally occurring sugars; maltodextrin is a sugar-like substance made from the processing of natural starches in rice, wheat, potatoes, or corn into long connected chains of glucose molecules.
This means that glucose, fructose, and sucrose are simple sugars, while maltodextrin is technically a complex sugar. Despite its relative complexity, maltodextrin can still be broken down and utilized by the body very quickly compared to other complex sugars.
Simple sugars each have specific transporters that allow them to get in or out of cells to be stored for later use, or to be used for energy production. Therefore, flooding the body with high amounts of only 1 type of sugar can create a backup in absorption; this can often be the cause of GI distress experienced while using sugar-rich sport products on the go. This unfortunate outcome can be a result of accidentally over-consuming certain types of one sugar, or taking in too many total sugars without other nutrients or adequate fluids.
Varying the types of sugar that you’re using in foods or sport products doesn’t only help reduce the risk of GI upset, but it also works to provide a more efficient, steady stream of fuel for working muscles, which can help protect the body’s need to dig into its sugar stores (glycogen) too soon, or to use them up entirely in moderate or longer efforts.
Outside of “isotonic” gel solutions (gels that have encapsulated water molecules), any sugar-rich food or sport product also requires fluids to allow for optimal rates of absorption.
Natural food sources of sugar are innately composed of some variety or types of sugars; very few, if any, natural food sources will have only one type of sugar molecule, sometimes making them innately easier for the body to absorb at a steadier rate than some processed products with less sugar variety. These food sources still require adequate fluids for digestion!
Sport food products are able to not only pick and choose the type of sugars they want to include, but also the ratio of sugars by weight for specific balances studied to be ideal for how each type of sugar is absorbed and utilized.
On average, when trained, we can typically absorb about 60 grams/hour of glucose or maltodextrin, and 30 grams/hour of fructose. Most products that include some combination of glucose/maltodextrin and fructose, therefore, typically aim to combine these in a 2:1 ratio to mimic the body’s rate of maximum absorption.
With this absorption rate, for those pursuing high-paced, longer endurance events (>4 hours), it is literally impossible for the gut to absorb the maximal volume of carbohydrates without mixing and matching different types of sugar each hour.
Typically considered “savory” items don’t necessarily miss the mark for meeting sugar targets. Snack foods like crackers, Goldfish, and pretzels or more traditional meal components like bread, potatoes, and white rice also include some natural or added sugars. Alternating more savory and slightly more complex carbohydrate sources into a fueling plan, especially during events >4 hours, can also help with the GI tolerance of many sugar-concentrated foods.
In addition to varying the types of sugars and volume of fluids in your race day fueling plan, it’s also important to remember that the body needs more total calories throughout long, hard efforts (running, cycling, rowing, skiing > 60-90 minutes) than sugar alone can provide. Including other nutrients like proteins, fats, and complex carbohydrates in small amounts for extended training or racing days is key to overall energy balance.
As with all things sports nutrition, practicing a variety of different types, timings, and amounts of sugars or sugar-rich products during training is the only way to truly toe the line at a race and know how your body’s energy levels, taste preferences, and GI tolerance will respond.
The one key area of overlap between sport fueling and non-athlete specific nutrition sugar recommendations is artificial and non-nutritive sweeteners. These processed sweeteners provide neither the necessary caloric fuel for energy production nor the potential benefit of additional nutrients; the most common examples you may see on food labels include aspartame, sucralose, saccharin, xylitol, steviol, and erythritol. Born out of a well-intentioned drive to reduce total caloric and total added sugar intake across cultural food consumption, artificial and non-nutritive sweeteners have crept into a majority of our processed foods, touting a “healthier” food product. These processed sugars can taste up to 300x sweeter than their organically-occurring sugar counterparts, potentially causing (ironically) the pattern of eating more calorically-dense sugars in order to mimic the volume of sweetness artificial sugars provide. Additionally, whereas natural sugars have a built-in “overflow shutoff valve” for absorption regulated by their limited volume of specified transporters, there is no parallel for artificial or non-nutritive sweeteners: the body does not have a regulating system to signal when the gut is satiated. This could result in replicating the same issue these sugars were originally designed to circumvent, and create a lack of adequate nutritive-carbohydrate intake, vital to the body’s ability to produce and store energy in and out of sport.
Sugar of any type, therefore, is certainly no exception to the health-boosting guidance of “all things in moderation.” As with any type of nutritional component, aiming to choose as many of our nutrients as possible from real foods first is always the safest starting point to supporting the body’s needs; for sweet foods in particular, when we choose sugars from whole carbohydrate sources, we’re often also consuming other types of carbohydrates (starches and fibers) as well as valuable micronutrients, like vitamins and minerals to support our overall health and performance goals. In moderate- to high- intensity sport, there may be some moments of practicality and efficiency that a processed sport food, with the right sugar balance, is the best way to fuel a high-performing training or race effort. Outside of sport, sticking primarily to whole, natural carbohydrate sources will provide the best balance of sugar quality and quantity.
Hungry for more information? Check out the links below.
Gatorade for Sport Science Institute: Multiple Transportable Carbohydrates & Their Benefits