Staying well-hydrated and eating particular foods before a triathlon can help ensure positive performance and recovery. The Academy of Nutrition and Dietetics recommends eating a variety of foods while training, keeping in mind that larger athletes who are training heavily may need well above 5,000 calories daily. Use your hunger and energy levels as a guide, or consult a sports dietitian to determine your specific calorie and nutrient needs.
Carbohydrates provide glucose -- the primary fuel for your body and muscles. For intense, heavy training, the Academy of Nutrition and Dietetics recommends aiming for 3.2 to 4.5 grams of carbohydrates per pound of body weight. For two to three days before intense events that last longer than 90 minutes, Colorado State University Extension recommends eating a high-carbohydrate diet because your body relies on stored carbs for fuel during exercise. Endurance cyclists, runners and swimmers benefit from a precompetition diet consisting of 70 percent carbohydrates. Choose primarily whole food sources of carbohydrates, such as whole grains, fruits and vegetables, which provide nutrients essential for proper function, including vitamins, minerals and fiber, and promote stable blood sugar and energy levels. Have oatmeal made with low-fat milk, a slice of whole-grain toast and fruit for breakfast, for example, on days leading up to your triathlon.
After carbohydrates, fats are your body's most important exercise fuel. For moderate exercise, about half of the energy you expend derives from fat in the body, says Colorado State University Extension. To make sure you have enough stored for use, your fat intake should not fall below 15 percent of your diet throughout training. Limit unhealthy fats, which are particularly prevalent in dairy products, meats and fried food, focusing instead on healthy, unsaturated sources, such as nuts, seeds, olive oil, avocados and oily fish. Avoid eating rich amounts of fat shortly before training sessions and your event to prevent gas, bloating and heartburn.
While it's only minor fuel for exercise, athletes' protein needs are slightly higher than nonathletes'. If your diet consists of 70 percent carbohydrates and 15 to 20 percent fat leading up to your race, that leaves about 10 to 15 percent of your total calories for protein. You can also rely on the Academy of Nutrition and Dietetics' guideline of 0.7 to 0.9 gram of protein per pound of body weight while engaging in heavy training. Don't eat too much protein just before your triathlon because it can deprive you of more efficient fuel and increase your fluid and oxygen needs. Instead, incorporate modest amounts of protein from nutritious sources, such as beans, legumes, fish and quinoa, a high-protein seed, into your meals and snacks.
Your Pre-Event Meal
Triathlons tend to start during early morning hours, so you won't likely have time to digest a hefty meal beforehand. Monique Ryan, a registered dietitian and author of "Sports Nutrition for Endurance Athletes," recommends energizing your body for a spring triathlon with a snack containing about 50 grams of carbohydrates within two hours before your event. Examples include 1/2 cup cooked oatmeal with a banana, an English muffin with 4 to 6 ounces of apple juice or a plain bagel. Two to three hours before a distance event, aim for a carbohydrate-rich meal containing about 500 calories, suggests Colorado State University Extension, such as two slices of bread, two slices of lean turkey and a piece of fruit. A smoothie provides a convenient option if you're strapped for time. For added hydration, have 2 cups of water a half-hour before the event and 2 to 3 cups with any pre-event meal.