Triathlon is a demanding sport in terms of nutrition, although it’s not fundamentally different from other endurance sports. The basics are that you need to consume an adequate number of calories, with a proper ratio of proteins, fats, and carbohydrates for each stage of your training.

On a shorter time scale, you need to make sure that you’re adequately nourished and hydrated before each workout, and that you have adequate recovery nutrition afterwards. For longer workouts and rides, you’ll need to eat and hydrate mid-workout.

This triathlon-for-beginners article presents all the basic ideas and tips on how to nourish and fuel yourself. 


Hydration: As a triathlete, you need plenty of fluids before and after every workout. If runs or cycling workouts go longer than 20 or 30 minutes, you need fluids during the workout as well. All your body’s systems need water; especially your cooling system, which works by letting water evaporate off your skin. This can happen at an alarming rate in hot conditions and when you’re exercising hard, so you have to work to keep hydrated. 

Be sure to drink before every workout, but don’t overdo it; if you fill your stomach with water faster than it can empty into your intestines, you’ll risk the discomfort of it sloshing around with each step. It’s best to drink relatively small portions over the 30 to 60 minutes before your workout. 

During the workout, continue similarly: small portions, frequently. Experiment while training to find a rate that your body can handle comfortably. 

And after the workout, drink up! You may be a bit dehydrated despite your best efforts, because in more extreme conditions your stomach can’t keep up with your cooling system. Now is the time to replenish.

Electrolytes: These are ionic chemicals that come from inorganic minerals. They include sodium, potassium, calcium, bicarbonate, magnesium, chloride, and phosphate. Electrolytes dissolve in the body’s fluids, and through properties of electrical conduction, they help modulate hundreds of vital functions. 

You lose electrolytes in your sweat, especially early in the season when your body hasn’t adapted well to warmer weather. If your electrolyte levels drop too low, you may experience fatigue, spasms, and eventually even seizures and heart rhythm disturbances. 

A healthy diet with plenty of fruits and vegetables is ordinarily enough to ensure electrolyte balance. During longer workouts in warmer weather, it’s often wise to use supplements. An easy way to supplement is with energy drinks or gels that include a complement of electrolytes.

Carbohydrates: These nutrients have been demonized by nutrition fads in recent years, but they’re literally what you run on. If you’re on a low-carb diet during training or racing, you’re not going to go very fast. So you’d be wise to get friendly with the sugars and starches that are collectively called carbs.

Protein: Proteins are the building blocks of your muscles. They’re necessary for maintaining and building strength. 

What exactly is protein? It’s a less straightforward question than you might imagine. Proteins are actually any combination of amino acids. There are 21 different amino acids used by the human body and they’re not all created equal. While the body needs them all, it’s capable of synthesising 12 of them, so you don’t need these in your diet. The remaining 9 you must get from food. 

These 9 are called the essential amino acids. You can get them from meat-based protein, or from a handful of plant-based proteins, including soy, quinoa, buckwheat, and seitan.

Otherwise, to get complete protein from plants, you need to eat foods in combination. Such as:

Legumes and Grains 

(rice and beans, peanut butter on whole grain bread, hummus on whole wheat pita)

Legumes and Nuts 

(salad made with beans and nuts)

You don’t even have to have your rice and beans in one sitting. As long as you have them over the course of a day, you’ll be fine. 

Proteins are especially helpful in recovery drinks (often in the form of protein powders based on soy, whey, or spirulina, added to a fruit smoothie). It’s not as critical to consume proteins during a workout. 

Fibre: Your body needs fibre for optimum cardiac health and gut health. There are two basic types.

Soluble fibre includes oatmeal, nuts, beans, apples, and blueberries. Benefits include cardiac health, reduced LDL cholesterol, blood sugar control, weight loss, and healthy bowel movements. 

Insoluble fibre includes the seeds and skins of fruit, whole grains, and brown rice. Benefits include weight loss and healthy bowel movements.

Probiotics: These are strains of healthy bacteria that join your gut biome and help with digestion. There are small doses of probiotics in yogurt with active cultures. For bigger doses, you can find probiotics in pill form. They may help treat digestive issues that don’t respond to anything else. They’re also helpful to quickly repopulate your gut if you’ve recently been on antibiotics. 

Caffeine: this natural supplement, resident in coffee, tea, and chocolate, is so useful to triathletes that it gets its own category. Caffeine not only acts as a stimulant, helping you to feel more alert and energetic, but it encourages the body to burn a higher ratio of fats to carbohydrates during long efforts. This translates into more endurance. 

For years, physiologists were worried that caffeine was a diuretic, meaning that it promoted dehydration. But recent studies have shown that in normal quantities of caffeine—like from a couple of cups of coffee in the morning, or a caffeinated energy gel every couple of hours— don’t dehydrate you. So there are really no downsides to caffeine on endurance workouts.

Other Supplements: there are dozens if not hundreds of supplements recommended as performance aids (also known as ergogenic aids) for athletes. Almost all of them are snake oil. They go in and out of fashion, and are routinely shown in clinical trials to have no effect. Anyone touting high-dose vitamins or minerals, branched-chain amino acids, CBD oil, or mystery powders is just trying to take your money. We’ve already covered the ingredients that work, if used correctly—namely, caffeine, protein powders, and electrolytes.

There are several varieties of ginseng (a plant root) that may offer subtle, positive effects for performance over the long term. It’s a difficult supplement to study, because it contains dozens of active chemicals, many of which seem to have opposite effects in isolation. One researcher commented, “we’re not sure what it does, but it seems to do something.”


Macronutrients are the proteins, fats, and carbohydrates mentioned above—they’re the nutrients that actually provide energy. You want to consume them in the right proportions.

There’s no one-size-fits-all correct macronutrient ratio. Your body uses these nutrients differently, and so the right balance is going to depend on what you’re doing.

You need proteins to maintain and build your body’s tissue, particularly muscle tissue. How much you need depends on how much recovery your muscles need to do. Strength training will increase your protein needs more than endurance training, which will increase them more than being sedentary. 


Don’t think about ratios of protein to other nutrients; just think about how much you need. For an endurance athlete this is around 1.3 – 1.8g per kilogram of your bodyweight.

For reference:

Sedentary people: 0.8 – 1.3g / kg bodyweight

Endurance athletes: 1.3 – 1.8g / kg bodyweight

Athletes doing high-intensity strength training: 1.8 – 2.4g / kg bodyweight

These recommendations are based on recent research and are significantly higher than recommendations from just a few years ago. They’re also much higher than recommendations from the World Health Organization and most national health organizations, which are more concerned with preventing malnutrition than with optimizing athletic performance. 

These recommendations are also based on high quality protein sources, which means ones high in branched chain (essential) amino acids, particularly leucine. This includes lean poultry, red meats, fish, whey, egg whites, and soy protein supplements. 

Vegan athletes should look specifically for plant-based foods rich in essential amino acids such as maize, brown rice, black beans, quinoa, oats, spirulina, lentils, and soybeans. Alternatively, they should supplement with soy protein powder, or simply increase their consumption of proteins beyond the recommendations above. 

If you are restricting your calories in order to lose weight while training, you should also increase your protein intake slightly beyond the recommendations. This will help minimize the loss of lean muscle mass.

Fats :

After you’ve worked out your protein needs, Fats should make up roughly 20 to 25% of your daily total calories. 


Carbohydrates should make up the rest. These are your primary source of fuel. Most of the energy you burn during your workouts should be compensated for with carbohydrates, particularly complex carbs (grains, tubers, pasta, etc.). 


Pre-Training and Pre-Race Nutrition

You’ll need to load up your body’s carbohydrate reserves before any long event, in order to maximise endurance. This involves eating piles of starchy foods during the 24 hours before the event. 

Nutrition During the Workout or Race

For any workout longer than an hour or so, you’ll need to supplement with carbs during the workout to keep your blood sugar up. You’ll need to ingest these even more slowly than pure water, otherwise you can overload your digestive system and get cramps. Generally, a few ounces every 20 minutes is the maximum. A sip of energy gel followed by a few gulps of water accomplishes the same thing. Energy gels and sports drinks usually also contain electrolytes, to help keep your systems balanced and reduce cramping. Some gels contain caffeine, to help your focus and fat metabolism.

If you suffer from stomach cramps or indigestion from your gel or energy drink, try smaller or less frequent doses. If the problem persists, try a different brand. There’s no one-size-fits-all recommendation for energy supplements. 

Recovery Nutrition

A carb-rich recovery drink, taken within 30 or 40 minutes of the end of your workout, will help replenish depleted carb stores in your muscles and liver. 10–20 g protein from soy or egg-white protein powder and some electrolytes (like from fruit) can be helpful.


There are many gaps in our knowledge of sports nutrition and nutrition in general. Experts recommend eating a variety, so you don’t get into a rut that could leave you deficient in some nutrients while possibly getting too much of others. 

Eat plenty of green vegetables. Eat a variety of them. Limit your intake of refined sugars, fruits, hydrogenated oils. 

Eat an adequate amount of fibre, including insoluble fibre (whole grains, fibrous vegetables, fruit skins) and soluble fibre (beans, bran, oats, citrus, apples, peas). Some people need more fibre than others in order to maintain bowel health. Others have limited tolerance, and develop digestive problems from too much. Just listen to your body. 

Since the gels and energy drinks we use while training are made from refined, processed carbohydrates, it’s a great idea to eat as much whole food and produce whenever possible. You can’t eat a bowl of broccoli during a 100-mile ride, so have it with your dinner!


Congratulations for getting through a rather technical and fact-filled article. Here’s a summary: eat well, eat and drink enough, but don’t try to eat or drink too much in the middle of a workout. Eat enough protein. Don’t fear the carbs—they’re your fuel. The more you train, the more carbs you need. Listen to your body. If a particular brand of gel or energy drink unsettles your stomach, try cutting back, or try a different brand. 

Good luck with your training! And happy eating.