For a 12-14 hour endurance event, nutrition is an incredibly important factor. In shorter distance events, you can get away with making some nutrition mistakes; during a double century, you are far more likely to feel the wrath of any nutrition errors. In fact, when you talk to athletes who did not have a good day, they will often mention nutrition as the main reason why things did no go as planned. Here, we’ll share the basics of endurance sports nutrition: a few general guidelines and some of the most common mistakes. (Note: For a deeper dive into nutrition-related questions and specific advice appropriate for your body weight, sweat rate, and fitness level, we recommend that you consult with a professional sports nutritionist or registered dietician.)


The main fuel for an endurance event like the double century is carbohydrate, especially the longer you are on the course. Your body stores contain roughly 500 grams of carbohydrate (2000 kcal), which is not enough to make it to the finish line without refueling. In theory, this should be enough to get most athletes through the first 3 hours of an event but topping up from the start is essential, because it takes time for carbohydrate to be absorbed. You need to start early with fueling to make sure you avoid carbohydrate depletion. Once you run out of carbohydrate stores it is extremely difficult to recover.

As a general rule, aim for 60 grams of carbohydrate per hour. This carbohydrate can come in the form of bars, gels, chews, or drinks. If you use solid foods, make sure fat, protein, and fiber content are low (no more than a few grams). What you use is entirely up to you and your personal preferences. Faster athletes tend to use more liquids and less solids because it can be difficult to chew solid food at high intensities.

To give you some idea of what 60 grams per hour equates to, it means that for every hour of the event you would need one of the following combinations:

– 2 gels and a small amount of sports drink;
– 1 gel and a bottle of a sports drink;
– 1 energy bar and half a bottle of a sports drink.

For more accurate calculations, check the nutrition labels of the specific products you plan to use.


“Drinking to thirst” is a recommendation that works fine for the slower-paced athlete. If you are pushing the pace, you’re better off armed with a plan. Use the early part of the race, when the gastrointestinal tract is working fine, to absorb both carbohydrate and fluid. Later in the race, despite your thirst, your gut may not absorb as much. Use common sense and drink what you need, but don’t drink excessively to the point where your stomach is in discomfort. In hot environments, pay extra attention to staying hydrated—you will likely need more fluids than in a temperate climate. Don’t forget that good hydration starts before the race; hydrate well and steadily in the days leading up to your event for the best chance of success on race day.

Gastrointestinal Issues

A large percentage of athletes—approximately 30-70 percent—experience gastrointestinal problems during Middle Distance triathlons. Some of these problems are minor, but some may be so severe that they affect performance. Some athletes are more prone to develop these problems than others. The complaints they experience may be totally independent of food intake and may only happen on race day. This suggests that “race day anxiety” plays a role in GI issues. Studies have also shown that factors like fiber intake, fat intake, and the use of highly concentrated carbohydrate drinks can cause gastrointestinal discomfort. Considering these three issues, you’ll be wise to plan ahead be familiar with your race day carbohydrate sources (drinks, gels, bars), how much fluid and fuel you need to take in, and where you’ll get it (carry it, utilize the aid stations, utilize your special needs bags). Make sure you reach approximately 60g/hour of carbohydrate intake and enough fluid to avoid losing much weight (more than 2-4 pounds of weight loss during a race can signal dehydration). To get a sense of your weight loss in relation to carbohydrate and fluid intake during endurance activity, weigh yourself before and after training.