How to Manage Triathlon Nutrition

It’s safe to say that the triathlon athlete is a unique individual. Who else would put themselves through the grueling training for not just one, but three different sports to come out on top with all of them? There is no weak area if you’re going to succeed. That’s what makes triathlon nutrition crucial to performance.

These athletes need more than the necessary calories to fuel everyday activities. They are pushing themselves beyond the limit of exercise to a new plane. The average active adult male age 35 requires about 3,000 calories, according to the Dietary Guidelines for Americans.  Depending on the event, a triathlon athlete may burn that amount in three hours or less.

Triathlon Nutrition

The triathlon as we know it today is a relatively new event, showing up in the 1920s in France before moving to the global stage. (Source) It consists of three stages that include swimming, biking, and running. You’ll see a lot of variation between the different types, but the bottom line remains that it is the sport of elite athletes. Over 4 million Americans take up this challenge each year, based on 2016 figures.

That means it will require higher physical and psychological needs for the individual. That means a greater supply of energy and adequate diet. A triathlon isn’t a one-off event. It also includes a rigorous training regime with additional demands for proper nutrition. The essential thing to remember is that the nutritional needs are not the same as the average person.

Physical Demands for the Sport

To put triathlon nutrition in perspective, let’s begin with the unique challenges that these athletes face. The sport puts the focus on the all major muscle groups of both the upper and lower body. That translates into a training schedule that will work all of them. A survey of non-elite triathletes by the Griffith University in Australia reported the following weekly averages (Source):

Swimming: 8.8 km

Cycling: 270 km

Running: 58.2 km

These figures set the stage for the special nutritional needs of these individuals. The most crucial one involves energy. The human body uses both fat and sugar in various forms to fuel its activities. It dances between different strategies with varying payoffs in the amounts that become available.

Adenosine triphosphate (ATP) is the energy currency that the body produces both in the presence and absence of adequate oxygen. It stores sugar or glucose in the form of glycogen in the muscles and liver. These are some of the sources that a triathlete taps into during a race to power high-intense activities. However, the demands for energy during a triathlon exceed the individual’s ability to supply it without replacing it during the competition.

Calorie Burn by Activity

Several variables affect the calorie burn by stage and, thus, the total energy use during a triathlon. Fuel demands are high because of the involvement of so many muscles, especially the larger groups. Let’s crunch some numbers of the calorie burn by activity and the individual’s weight. The events along with their respective distances we’ll consider include:

Sprint (500 yards swimming, 13 miles biking, 3.1 miles running)

Olympic (1,500 yards, 24.8 miles, 6.2 miles)

Half-Ironman (2,100 yards, 56 miles, 13.1 miles)

Ironman (4,200 yards, 112 miles, 26.2 miles)

As you can see, this competition is not for the faint of heart even at its lowest level. The average American diet won’t make the cut, but let’s see how far it falls short.


Triathlon swimming puts the emphasis on the upper body. From a nutrition perspective, they probably get adequate vitamin D from sun exposure during training outdoors.  The approximate calorie burn is as follows based on an individual weighing 180 pounds (Source):

Sprint: 109 calories

Olympic: 340 calories

Half-Ironman: 504 calories

Ironman: 1,048 calories

Other factors can influence these amounts including speed, conditions, and fitness of the athlete. However, it’s worth noting that this part has the smallest calorie demand of the three.


Cycling has the highest demand for fuel of any of the activities. Biking and swimming share a common trait in that neither are weight-bearing activities. Bone density becomes a concern that will, in turn, influence triathlon nutrition. The approximate calorie burns include (Source):

Sprint: 773 calories

Olympic: 1,622 calories

Half-Ironman: 3,052 calories

Ironman: 5,719 calories

The energy demands reflect the involvement of both the upper and lower body in this activity. Factors influencing include fitness, type of bike, your use of aero position, and terrain.


Triathlon running is the final test of the triathlete. While it requires less fuel, it remains demanding nevertheless. The approximate counts are (Source):

Sprint: 427 calories

Olympic: 845 calories

Half-Ironman: 1,767 calories

Ironman: 3,568 calories

The calorie burn during the run will also vary because of many of the same factors influencing the cycling portion. However, the numbers still tell an impressive story. When we put it all together, the results are astounding and put the spotlight on these elite athletes. Based on these figures, the total calorie burn is about:

Sprint: 1,309 calories

Olympic: 2,807 calories

Half-Ironman: 5,322 calories

Ironman: 10,335 calories

At this point, it’s probably apparent that caloric intake is a major factor in nutrition. But it isn’t a matter of just eating a lot to make up for what you’ll need during the race. There’s also triathlon training to consider too. These things put carbohydrate, protein, and nutrients in the spotlight. And just like your preparation, it requires careful consideration about the best tweaks you can make in your diet to best support your efforts.

Plant-Based Diets

Vegetarians and vegans will have additional needs because of their dietary restriction (Source). The main concerns will rest with adequate protein and certain nutrients which we’ll discuss in detail below. Let’s jump into what triathletes need to know to compete at their best from a nutritional perspective.

Pre/Post Workout Triathlon Nutrition

Any healthy can participate in a triathlon—as long as they’re willing to put in the time and effort. Even beginner triathlon training is going to place demands on your personal and professional life. Often individuals new to the sport focus only on the activities and ignore the importance of a good diet. It is, after all, just as vital to your performance as the time spent swimming, cycling, and running.

It’s essential to realize your diet must support your training because these activities will demand so much of you. In a way, what you eat trains your body to be more efficient at processing energy or ATP. It adapts readily to the increases in calorie burn and exercise. It’s one reason why some individuals plateau when they try to lose weight if working out is a part of their plan.

The challenge with the triathlete is the polar opposite. They must eat enough to maintain their weight and not shed too many pounds because of their intense workouts. That means you’ll need both an eating and training schedule. You’ll have to replenish nutrients to speed muscle recovery to support your performance and maintain your fitness level.

Several small meals spaced throughout your day is the best way to ensure adequate energy and stable blood sugar levels. While carb-loading is a thing, it’s not the ideal plan for maximizing the benefits of a healthy diet. You should plan on fueling your training before you begin to put yourself on good footing.

Fatigue caused by inadequate food or fluid intake is the bane of athletes, especially the triathlete who must meet a time goal. It can slow your performance and leave you more vulnerable to injuries. Let’s review what your diet should include along with the amounts to support your training.


Your body can obtain fuel directly from the glucose or sugars in the foods you consume. It can also metabolize its stored energy in the form of glycogen. That means choosing high-quality, nutrient-dense dietary sources. The recommended daily allowance (RDA) for carbohydrates is 130 g a day for adults. That’s the minimum your body need to function adequately.

The average intake hovers around 220 g for men and 180 g for women based on the consumption of other nutrient-rich foods. In any case, the fact remains that your brain uses about 20 percent of the sugar you take in from your diet. It’s probably clear to see why low-carb diets are a bad idea for losing weight. Your neurological system won’t tolerate not getting enough. For the triathlete, it’s critical.

It’s helpful to look at in terms of a percentage of the total caloric intake to determine what is adequate for these athletes. Remember, these individuals will consume more than the average person based on their increased energy demands. The Dietary Guidelines for Americans recommend that adults get between 45 and 65 percent of their calories from carbohydrates. The range reflects the needs of different activity levels.

A gram of carbohydrate equals about four calories. If we do the math, that translates into about 225 to 325 g per day based on a 2,000-calorie daily diet. A triathlete will likely lean more toward the high end of that RDA range along with a greater intake that approaches 3,000 calories. That puts it closer to 487 g per day or about 1,950 calories.

Quality Sources of Carbohydrates

Triathlon nutrition relies on good sources of these nutrients. There are several types of carbohydrates that include:





Simple carbs include sugary snacks. Nutrient-dense sources are fruits which provide better types of sugars. Complex carbs are legumes and whole grains. Starches are foods such as potatoes and corn. Finally, fibers include both soluble and insoluble sources with overlap between the others listed.

And contrary to popular belief, it’s essential that the individual eats before working out to prevent drops in blood sugar and energy that could affect performance and muscle recovery which are its primary purpose. You shouldn’t skip this pre-workout meal.

Sports Drinks

Sports drinks are an essential part of the athlete’s diet. Their role is to maintain adequate levels of electrolytes like sodium and potassium. The importance of these nutrients can’t be overstated. They are vital for even the most basic life functions such as heart rate and breathing. An individual will lose significant amounts when exercising, especially during intense activity.

However, the optimal choice is a personal one. Each beverage contains its own blend of electrolytes, sugars, and proteins. Balance with the athlete’s physiology comes into play when choosing which works best. Some may have trouble metabolizing certain ingredients that can lead to GI distress. That means some experimentation and adaptation is part of the process to homing in on the right sports drink.

As we mentioned earlier, the human body can’t keep up with the energy needs during endurance activities like triathlons. The individual will need to replenish their stores of electrolytes during training or a competition. Failure to do so can result in a potentially life-threatening condition called hyponatremia or low blood sodium levels. (Source) It’s one reason why drinking only plain water won’t cut it.

It’s important to stay hydrated during activity and not to wait until you feel thirsty. That can have the opposite effect if you consume too much. It’ll result in nausea which will also hamper your performance.

Protein Intake

Proteins aren’t an important source of energy for the body. However, if an individual isn’t getting enough from other foods, it’s fair game that has some serious consequences. These nutrients consist of chains of chemicals called amino acids. They are, in turn, the building blocks for other proteins including hormones, enzymes, and antibodies.

They include nine essential amino acids that your diet must supply since the human body can’t synthesize them. That makes meeting the RDA important whether you’re an athlete or not. Remember, these are the ingredients for the other proteins that are crucial for life itself.

The triathlete puts immense demands on their body, making adequate protein intake vital. The Dietary Guidelines for Americans recommends that proteins make up between 10 and 35 percent of your daily caloric intake. For non-athletes, about 0.8 g per kilogram of body weight will meet their nutritional needs. However, it’s a different story when it comes to triathlon nutrition.

The stance of the International Society of Sports Nutrition (ISSN) is that an intake of 1.4 to 2.0 g protein/kg body weight/day is more in line with the specific needs of these individuals, even more in some cases. It isn’t because of energy needs.

Rather, it’s because of the recovery process. An athlete will damage muscle fibers during a triathlon run because of the intense activity. Protein is essential to aid recovery and maintain muscle mass, two vital criteria for a triathlete. Again, there is the need for balance in terms of meeting the physiological needs and exceeding them.

Running is part of the justification for the higher protein requirements. This weight-bearing activity can damage red blood cells, necessitating a need for more protein to replenish hemoglobin stores, the chemical that transports oxygen in the blood. However, we still need to consider fat, so protein intake must strike a balance with it as well.

A diet that includes 20 percent of calories from protein will provide about 150 g based on a 3,000-caloric intake for an athlete. That’s nearly three times the amount recommended by the USDA guidelines. But, again, we’re talking about individuals who activity levels far exceed those of the average American adult.

Quality Protein Sources

The operative word when it comes to getting adequate protein is lean. These sources are easier to digest and deliver their nutrient and energy content quicker. That is the key to healthy triathlon nutrition. Every meal except the pre-exercise snack should contain some protein. Ideally, your diet will include a myriad of sources from fish to meat to low-fat dairy products. If you are vegan you can get ample protein from vegetables and nuts as well.

These foods will not only aid recovery but also help you feel sated after eating. They will also help maintain blood glucose levels because they take longer to metabolize than simple carbs. The importance of balance in terms of diet is imperative for optimal performance.


Fats contain over twice the amount of calories per gram as either carbs or proteins with 9 g. On the positive side, they’re an excellent source of energy, especially during low-intense activities. They contribute to satiety. And like the other macronutrients we’ve discussed, they are essential for a healthy diet. Your body needs fat to absorb certain kinds of nutrients like vitamins A and D.

The downsides rest with two other factors, effects on performance and possible health risks. Think of how you feel after a heavy meal. The last thing you want to do is compete in a triathlon. Sleeping is more in order to digest your food. While fats provide fuel, it takes longer for your body to metabolize them. They stay in your system longer which can lead to GI distress during training.

The other concern focuses on the type of fat you consume. Unsaturated fats include healthy sources such as olive and canola oils. Nuts are another important source. These foods can protect your heart and cardiovascular system while providing the benefits for which they are known.

Saturated fats, on the other hand, can raise your levels of bad cholesterol or LDL. That can, in turn, increase your risk of heart disease and diabetes. For the triathlete, it’s not worth compromising your health when you have better alternatives to get adequate amounts in your diet.

Changing Metabolism

We’ve spoken before about how your body adapts to exercise. It is also evident in the way it produces energy. Before training, carbohydrates are the athlete’s primary source of fuel because they’re easy to digest and use. Over time, the number of mitochondria increase. You can think of them as the power plants of the cells.

Your body will also shift its reliance on energy sources. Carbohydrates still will remain important, but it will also ramp up its use of intramuscular triglycerides. These are fatty acids that you get from the foods you eat. As you probably know, your body stores excess fat. Other than the obvious, your muscles will also contain the extra amounts you consume in this form.

Training increases your body’s ability to tap into these stores of energy as long as adequate amounts of oxygen are present. Your body will metabolize the fatty acids to produce heat and ATP. The long-term result is better endurance. That’s only of the primary goals of all those hours you spend working out before the race. In the end, your efforts will pay off big time.


We’ve already discussed the importance of vitamin D. One of the best non-dietary sources is sun exposure, albeit, not without its health risks due to its association with skin cancer. However, inadequate amounts can impair calcium absorption which is why you often hear of the two mentioned together. It is the most abundant mineral in your body for a good reason.

Calcium is essential for many basic life processes including muscle, nerve, and circulatory system function. If your body is lacking, it’ll go to your stores of it in your bones and teeth to get what it needs to survive. It’s that important. Therefore, it’s vital for the triathlete to get enough from a healthy diet to maintain bone density.

Think of all the stress your skeletal system endures while trying to improve your time for even a 3.1-mile run much less a 26.2-mile Ironman. All of that training means that your body may need more than the RDA of 1,000 mg. For the triathlete, 1,300 to 1,500 mg is a wiser strategy for added insurance of good bone health. Excellent dietary sources include:


Mozzarella cheese



Calcium-fortified soymilk

To stick within your calorie budget, make sure to choose low-fat options.


You should have potassium intake on your radar because of the risk of depleting stores during sweating. It’s part of the reason why sports drinks are so important while training for a triathlon. This mineral has one of the highest RDAs of any nutrient at 4.7 g per day. It has several vital roles in body function including water and pH balance, electrical activity of the heart, and protein synthesis. Dietary sources include:

Citrus fruits





There are, of course, individual variables involved with this nutrient. That’s why the serious athlete should consider consulting a professional dietician to help plan your diet to include all the necessary vitamins and minerals.

Vitamin C

Vitamin C is a water-soluble nutrient.  That means that the human body doesn’t store it. You need to get an adequate amount in your diet every day. It’s especially important for the triathlete because of the roles it plays that directly impact your performance. First, it’s vital in the process of getting fatty acids to the mitochondria in your cells to produce energy.

Second, it plays a role in the synthesis of chemicals called neurotransmitters that can speed the metabolism of the stored form of sugar, glycogen, into glucose for fuel. Finally, it’s crucial for collagen formation. That is the connective tissue that makes up your skin and muscles. It also helps with wound healing including delayed onset muscle soreness or DOMS. Excellent dietary sources include:

Citrus fruits

Red peppers



The RDA is 90 mg a day for men and 75 mg for women. However, athletes should bump their intake up to 200 mg because of the added stress on their bodies. You should not exceed that amount. So-called megadoses will not improve your health or prevent disease. They may cause GI distress in some individuals. Just remember what we said about your body not storing it, and you’ll get the picture.

B-Complex Vitamins

This group of nutrients is also water-soluble, meaning daily intake is imperative. Many including thiamin (B1), riboflavin (B2), and niacin (B3) support energy metabolism which is essential for serious athletes. Meeting the RDAs of these vitamins will provide adequate amounts in most cases.

Fruits and vegetables are rich sources. You should consume a wide variety, ideally, in a broad spectrum of colors. It’s preferable to taking a dietary supplement to meet your body’s needs for them.

The exception to that statement involves vitamin B12. The primary sources are animal-based which could present an issue for vegetarians who compete in triathlons. It is essential for protein synthesis and red blood cell formation. It’s one time where a supplement may be necessary to support your training.

Triathlon Nutrition for Race Day

A triathlete should consume carb-rich foods throughout their day to support their activity levels and training. That will mean frequent meals to maintain blood glucose levels, especially when exercising.


Sodium is an anomaly when it comes to the RDA and the triathlete. Adequate intake (AI) is 1.5 g per day. You’ve probably heard that the average American diet exceeds this amount—by a lot. While getting too much is associated with heart disease risk factors, not getting enough is more of a concern for those training and participating in triathlons.

Sodium, like potassium, plays a crucial role in water balance. That’s at the root of all things human. Athletes are at risk for losing large amounts through perspiration. Other things can affect the rate too including hydration status, acclimatization to the heat, and other environmental factors. However, abnormally low levels in the blood are potentially life-threatening as we discussed earlier.

The Institute of Medicine, which is part of the body of scientists that set nutrients recommendations, recognizes the unique situation that exists between athletes and sodium intake. In short, the AI does not apply to these individuals. Instead, intakes greater than 1.5 g per day are the norm with amounts as high as 10 g if excessive sweating is an issue especially with the added demands of race day.

Nutrition Tips During Race Day

Triathlon nutrition is all about maintaining balance and providing your body with adequate fuel to perform at its best. Triathletes have different needs than the average adult. Over 27 percent are inactive and engage in no physical activity. These athletes are a unique subset of the population. The varying requirements for caloric intake, macronutrient percentages, and nutrients reflect these facts.

Fluid Intake

Staying hydrated is imperative for athletic performance. The best strategy is to drink moderate amounts of water throughout your day. That will maintain the proper fluid balance in your blood volume. It will aid digestion and keep your GI system functioning well. One mistake that beginners sometimes make is letting their thirst drive how much they consume.

It’s important to bear in mind that thirst is a red flag that your body uses to alert you that your fluid levels are getting low. It occurs as a warning after you may have already lost 1 ½ to 2 liters. That’s a major problem for an athlete because the first thing you’ll want to do is gulp down a glass of water to rehydrate.

A much better strategy is to drink water or a sports drink at least an hour before you train or race. That will give your body enough time to absorb it and redistribute it and the accompanying electrolytes through your tissues. It’ll put you in the optimal state to work out rather than letting thirst call the shots. You should continue to drink fluids during exercise to maintain adequate levels.

Other Nutrient Needs

Generally, your body’s requirements for other nutrients will increase with your activity level. There are several reasons for these changes. First, you’re demanding more of your body. It will need the raw materials to get the job done. Second, the needs for nutrients to aid in recovery and maintenance of fitness levels also rise. Third, your muscle mass will bulk up and need the energy to sustain itself.

Finally, triathlon nutrition must address the special needs of these athletes because of their chosen sport. You’ll find that the necessary intake of some vitamins and minerals will exceed the amounts that the average person requires because of the combination of all these factors. As long as you eat a varied, healthy diet, they shouldn’t present a problem. Let’s review a few that you should know.

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