Competing in an Ironman is no small feat—it demands physical endurance and a strategic approach to nutrition. Often called the fourth discipline of triathlon, nutrition plays a crucial role in overall well-being and performance, alongside swimming, cycling, and running. Without a proper nutrition strategy, you may struggle during preparation and on race day. However, with time, you’ll learn to listen to your body and realise that healthy eating doesn’t have to be stressful or boring.
Juliana Lustosa, a registered holistic nutritionist, Ironwoman and mother of two, knows this firsthand. She placed 4th in her age group at Ironman Queensland in 2023, securing a coveted slot at Ironman Kona—an impressive feat, considering that
only three percent of age group athletes qualify for the Ironman World Championship. In this blog, she shares expert nutrition tips and insights on what it truly takes to fuel endurance, optimise recovery, and complete an Ironman.
Juliana Lustosa, a seasoned Ironman competitor.
1. Prioritise a Balanced Daily Diet to Support Your Training
Many athletes focus heavily on what to eat before, during, and after training, but the foundation of their performance lies in their overall daily diet. Their meals should align with the volume and intensity of their training to ensure sustained energy, recovery, and optimal performance. Don’t eliminate entire food groups—each plays a vital role:
- Carbohydrates are your primary fuel source, replenishing glycogen stores and preventing fatigue during long training sessions. Prioritise whole grains, fruits, and vegetables, which also provide antioxidants to reduce inflammation and muscle soreness. While refined carbs (like pasta, noodles, and cookies) can be included in moderation, they shouldn’t be your go-to fuel source.
- Protein is essential for muscle recovery. Include a variety of sources, such as lean meats, fish, eggs, and dairy, as well as plant-based options like tofu, grains, and legumes.
- Healthy fats support hormone balance and energy levels. Incorporate nutrient-rich sources like nuts, seeds, avocados, and olive oil into your diet.
Focus on natural, whole foods and minimise processed and refined options. Drink plenty of water throughout the day, and if you’re training in a hot and humid climate, consider supplementing with electrolytes to maintain optimal hydration and performance.
2. Fuelling for Performance: Pre-, Intra-, and Post-Workout Nutrition
2.1 – Pre-Workout Nutrition
Training on an empty stomach, also known as fasted training, is often thought to promote fat burning. However, for most people—especially women—it can lead to negative effects such as muscle loss, hormonal imbalances, reduced performance, and unstable blood sugar levels. That’s why I don’t recommend it.
- Additional fuel may not be necessary for training sessions lasting less than an hour.
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For longer sessions, aim to eat a balanced meal with carbohydrates, protein, and a small amount of fat 2–3 hours before training. Some examples include:
- Sweet potatoes with scrambled eggs and a fruit of your choice.
- Banana smoothie made with protein powder, oats or oat milk, and peanut butter.
- 30 minutes before training, consume a quick and easily digestible carbohydrate source, such as a banana or an energy gel.
2.2 – Fuelling During Training
Electrolytes are important—strive to drink 500–750ml of fluids per hour, adjusting intake according to your sweat rate and the surrounding conditions.
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For workouts lasting over 80 minutes, aim to consume 30–60g of carbohydrates per hour to maintain energy levels. Suitable options include:
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Energy gels, chews, or sports drinks
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Whole food choices like dates
Depending on the intensity and duration of your workout, you may need a higher carbohydrate intake.
- Electrolytes matter. If needed, supplement with sodium through sports drinks, salt tablets, or electrolyte mixes.
- For optimal hydration, aim to consume 500–750ml of fluids per hour, adjusting as needed based on your sweat rate and environmental conditions.
2.3 – Post-Workout Recovery
- Replenish carbohydrates and protein within 30–60 minutes to optimise muscle recovery and restore glycogen stores.
- The ideal carbohydrate-to-protein ratio for recovery is 3:1 or 4:1; examples include a smoothie with banana and protein powder and rice with eggs.
- Hydration is key. Continue to drink water and replenish electrolytes, especially after long or intense sessions.
- If your workout ends around mealtime, your post-workout meal can be a complete, balanced meal to support recovery.
3. What Supplements Are Worth Investing In?
With the vast array of sports supplements on the market, it can be challenging to determine which ones are safe and truly beneficial. Based on strong scientific evidence, my top five recommended supplements for endurance athletes are:
- Beta-Alanine – Helps delay muscle fatigue and improve endurance.
- Creatine – Supports muscle strength, recovery, and overall performance.
- Caffeine – Enhances focus, reduces perceived effort, and boosts endurance.
- Glycerol – Aids in hydration and fluid retention, particularly in hot conditions.
- Nitrates – Improve oxygen efficiency and endurance (found naturally in beetroot juice).
In addition to supplements, sports-specific nutrition products such as protein powders, sports drinks, carbohydrate gels, electrolytes, and essential vitamins and minerals can help support overall health, energy levels, and performance.
4. Race Day Strategy: Fuel Smart, Perform Strong
Juliana Lustosa and her family at a multi-sport event.
Race day is not the time for experimentation—stick to the nutrition and fuelling strategies you’ve practised during training. Carb-load wisely in the 2–3 days before the race by gradually increasing your carbohydrate intake without overeating. This helps maximise glycogen stores for sustained energy on race day. Additionally, following a well-planned nutrition strategy will enhance your performance, improve recovery, and keep you feeling strong and energised throughout the race. With the right nutrition plan, you'll perform better and enjoy the Ironman journey to its fullest.
Featured Contributor:
Juliana Lustosa
Registered Holistic Nutritionist
As a Registered Holistic Nutritionist and Triathlete, Juliana equips you with a personalised Nutrition plan, supplements recommendation (on a by need basis) and education on how to obtain total body fitness and better quality of life.
With her personal journey as a triathlete for over 15 years, Juliana knows what it takes to last long in an endurance sport.
After giving birth to twins, she experimented with nutrition to create solutions to account for how the body changes over the years. This paves the way so you are not only in the game today but for the foreseeable future.
Juliana works with athletes of all levels, from beginners to experts. Together, you will review your personal journey, goals, history, achievements, possible nutritional imbalances and then, set a nutritional plan to achieve results for better performance, quality of life and longevity in any sport or fitness goal.
Connect with Juliana on Instagram.