Four Pillars of Nutrition in Triathlon Training



Nutrition plays a key role in your ability to train, recover, and perform at your best. Top endurance athletes know that the optimal nutrition for training is not the same as the optimal nutrition for recovery, or for racing! Fueling for the endurance athlete can be broken down into four main pillars:

  • Daily nutrition
  • Training nutrition
  • Race week nutrition
  • Race nutrition

This post will highlight some of the key aspects of each of these areas. If there are dimensions you’re not considering, you might be leaving sometime on the table during your next race!

Pillar 1: Daily Nutrition

Our day-to-day nutrition intake plays a role in how recovered we feel between training sessions, what kind of fuel we burn during our workouts (fat vs. carbs), and our body composition.

Protein Intake

For most athletes, a target of 1.6–2.2 grams of protein per kg of body weight should be appropriate. Ideally, this would be split relatively evenly across 3–5 servings throughout the day. For someone weighing 70 kg (154 lbs), this means four servings of 35 g protein would have you covered quite well but you do have some flexibility with this.

A recent study in endurance-trained men (training ~6 to 10 hours per week) fed them varying amounts of protein per day, to determine just how much protein their bodies were capable of using. As you see below, they were utilizing up to around 2.1 g of protein per kg of body weight (0.95 g per lb). Each of the symbols represents one of the eight subjects, who each consumed several different protein intakes on different days.

In the picture below, as long as the line is increasing protein is being used. When the line flattens out, it means the body is no longer needing that additional protein. This means the average protein requirement would be 2.1 g per kg of body weight (0.95 g per lb), and the recommendation that would cover 95% of the population would be 2.6 g per kg (1.2 g per lb).

Carbohydrate periodization

The proportion of carb and fat intake can vary depending on the individual, their personal preferences, and the type and amount of training being done. Regardless of whether someone is following a higher or lower-carbohydrate diet, the current best practices in sports nutrition support the idea of carbohydrate periodization – varying your carbohydrate intake depending on your training. Just like you don’t do the same type of training each day, it wouldn’t make sense to eat the same each day. This means you should be increasing carbohydrate intake around longer or harder training sessions, and decreasing the amount around shorter or easier sessions.

Within-day energy balance

This is an important, yet often overlooked concept that describes the balance throughout the day between food intake and energy expenditure. People are often only focused on total daily calorie balance, but it is easy to imagine that it might not be ideal if someone does a very big workout in the morning but doesn’t eat anything until dinner where they make up for all of their daily calories. This can have negative effects on your hormones and body composition. Instead, aim to eat more of your calories around your workouts, and a bit lighter away from your workouts.

For example, the table below shows a typical day for an endurance athlete. The line indicates energy balance throughout the day. When we wake up in the morning, we are already in a small energy deficit because we haven’t eaten since the previous evening. Now let’s say you do a workout around 6 am, without eating anything. You could easily burn 400-1200 kcal during a 1 hour workout. Even if you eat a large breakfast afterwards you could still be in a calorie deficit until lunch time. While deficits are not inherently bad, we just want to avoid spending too much time in too large of a deficit. Larger within-day energy deficiencies have been associated with hormonal dysfunction and even a reduced metabolic rate in both male and female endurance athletes.

Pillar2: Training Nutrition

In line with the concept of carbohydrate periodization, what you consume during training sessions should also vary depending on the length/duration of the workout, and also on what part of the season you are in.

Low-fueled Sessions

Many athletes perform exercise in the fasted state, for a variety of reasons ranging from a desire to increase their fat oxidation to simply convenience. Keeping in mind the concept of within-day energy balance discussed above, you may want to consider a low-carbohydrate snack prior to training that you otherwise might have done in the fasted state. Consuming protein and/or fat before exercise won’t meaningfully alter your fat oxidation in the same way that a pre-exercise carbohydrate meal would but will help reduce your morning energy deficit.

The duration and intensity of the exercise session should be considered when considering the best pre-exercise nutrition choices. Before shorter duration exercise sessions that focus on lower intensity steady-state training, it may be beneficial to withhold carbohydrate, while there is little evidence supporting carbohydrate restriction before high-intensity exercise. For longer duration exercise (>90 min), there is little evidence to suggest carbohydrate-restricted training offers any additional benefit.

Evolving Your Race Day Nutrition Plan

One of the first things people are told when they begin competing in races is “never try anything new on race day”. This applies not just for the types of food/drink you consume during a race, but also for the amounts! Your long rides/runs are a great chance to practice and evolve your race day nutrition plan throughout your block of training. Is 40–50 grams of carbohydrate right for you? Or closer to 75–90+ grams per hour? Should it be from solids? Liquids? Gels? These are all things that should be tried and adjusted until you are fully dialed in. Many athletes take ‘more’ during race day, but you should have enough experience from training with your ‘race-day’ intake.

Pillar 3: Race Week Nutrition

The week before a race is about getting your body recovered, refueled, and ready to go!

Carbohydrate Intake

It is widely agreed upon that increasing your carbohydrate intake in the days leading into a race is a good thing. However, the specifics of a carb-load will vary greatly depending on your typical daily carbohydrate intake, body composition, and fitness level. Your training will typically be tapered down, which means your calorie needs won’t be as high. Rather than simply adding more carbs to your normal diet, you can also cut back slightly on the protein and fat so you can consume some additional carbs without feeling like you’re over-eating.

Fiber Intake

During the last 2-3 days before race day it can be a good idea to reduce your dietary fiber intake. This can reduce the likelihood of gastrointestinal (gi) issues during your race, and even reduce your weight slightly.


This is not for everyone, but if you struggle with gastrointestinal issues during exercise, it may be useful to do this for a week going into a race (ideally while working with a qualified sports dietitian). A low-FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) diet removes certain types of (otherwise healthy) fibers and can offer improvement for a variety of IBS-related symptoms that can occur during exercise.

Pillar 4: Race Nutrition

Planning Ahead Go into your race with a specific fueling plan—the one you’ve evolved during training sessions. It is okay to leave some options open, that may be weather-dependent (e.g., which could change your fluid needs), or just based on preference (e.g., the order in which you eat your gel/chews/etc.). Following a specific plan has been shown in multiple research studies (here, here, here) to be better than eating/drinking based on how you feel.

Calories per Hour vs. Carbs per Hour

Your hourly nutrition intake should be thought of as the amount of carbohydrate per hour, not calorie intake, which can be very misleading. During most endurance events (lasting 1–2 hours up through Ironman-distance triathlons), the hourly intake of carbohydrate matters far more than the hourly calorie intake. While consuming 50 g of carbohydrate per hour from sports drinks can accurately be referred to as 200 kcal per hour, consuming 200 kcal per hour of mostly fat and protein will have a completely different effect on your body (and performance). Focus on the carbs, not calories!

Fat, Fiber and Protein

Building on the last point, during events lasting less than ~16 hours, we do not need to consume very much dietary fat, fiber, or protein. While there may be a potential benefit to consuming small amounts of amino acids during extended endurance exercise, consuming fat and fiber adds unnecessary work for the gut without providing anything useful to the muscles, and has also been associated with symptoms of GI distress during exercise.

Do you have all of these nutrition pillars covered? If not, there may be a great opportunity for you to gain some time in your next race! Happy training and racing!

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