reboot blog

How to plan your nutrition during a 100-mile race

A 100-mile race is an eating exercise as much as a running event. The distance exposes every weakness in your fuelling strategy: a breakfast that sits heavily, a gel you cannot face after 12 hours, or a missed aid station can turn manageable fatigue into a long night of damage control.

The aim is not to discover a perfect menu. It is to create a repeatable system that supplies carbohydrates, fluid, and electrolytes while remaining flexible enough for heat, hills, poor appetite, and changing race conditions. Your plan should help you keep moving at a sustainable effort rather than chase a precise number at every checkpoint.

Training provides the useful evidence. Long runs, back-to-back weekends, and overnight sessions show which foods you can digest, how much you drink in Australian weather, and when your appetite changes. A race plan built from those observations is far more reliable than copying the nutrition strategy of a professional runner.

Start with energy targets you can actually use

Carbohydrate is the primary fuel for a long ultra. A practical starting point for many runners is 60–90 grams of carbohydrate per hour, although the right amount depends on body size, pace, intensity, heat, and gut training. Beginning at the lower end is sensible if you have rarely practised fuelling, then increasing gradually during training.

Think in terms of an hourly menu rather than a single product. One gel may contain about 20–25 grams, a sports drink another 20–30 grams, and a small rice cake or banana roughly 20–30 grams. Combining these items makes the target easier to reach and reduces the risk of becoming sick of one flavour.

The first hours often feel easy, which can make runners under-eat. Start fuelling in the first 30–45 minutes, before hunger appears. Small, regular servings every 20–30 minutes are usually easier to absorb than a large amount taken after several hours of neglect.

Your pace also matters. A runner moving steadily through an alpine course may need more carbohydrate than someone walking much of a hot, technical section, but both need enough energy to protect decision-making and movement quality. Use the target as a range, not a test that creates anxiety.

Build a menu around different textures

Sweet gels are convenient, but a 100-mile race can last through two meals and a night. Many runners reach a point where another sugary mouthful becomes impossible. Include savoury and solid foods from the beginning, then adjust the balance as the race progresses.

Useful options include boiled potatoes with salt, rice balls, soft wraps, bananas, oat bars, pretzels, soup, and small sandwiches. In Australia, a Vegemite sandwich cut into small squares can be a practical aid-station or crew food if you have tested it. A simple white-bread sandwich is often easier to digest late in a race than a high-fibre muesli bar.

Keep early-race food relatively familiar and low in fat and fibre. As intensity falls and walking increases, you may tolerate more solid food. A cup of noodles, broth, or a small cheese sandwich can feel appealing overnight, but rich foods and large portions can cause trouble when the stomach is already slowing.

Create a short menu for each stage:

This approach gives you variety without turning every checkpoint into an improvised buffet. Pack foods in small portions so you can eat a little, return them to a pocket, and continue moving.

Match drinking and electrolytes to the conditions

Fluid needs vary widely, so avoid using a fixed number simply because it appears in a race guide. In cool conditions, some runners may manage around 400–600 millilitres per hour; in hot or humid weather, requirements can rise. Drinking far beyond thirst can be dangerous, particularly when sodium intake does not match the fluid volume.

Sweat rate testing gives you a useful estimate. Weigh yourself before and after a training run, account for fluid consumed and urine loss, and divide the change by the duration. Repeat this in different conditions because a cool Melbourne trail run will not represent a summer event near Brisbane or an exposed Western Australian course.

Electrolyte products vary considerably. Check the sodium content of your drink mix rather than assuming that a product labelled electrolyte contains enough. Endura, Pure Sports Nutrition, and imported products such as Tailwind or Precision Fuel are available through the Australian market, but their concentrations differ. Choose based on tested tolerance and the race’s water access, not branding.

Some races provide water, sports drink, cola, and ice, while others have long gaps between aid stations. Ultra-Trail Australia in the Blue Mountains, for example, can involve steep terrain and changing temperatures even when the forecast looks mild. Carry enough fluid capacity for the longest section, and treat the event’s official aid-station information as part of your nutrition plan.

Turn aid stations into simple routines

Aid stations are places to refuel, refill, and make decisions, not automatic rest stops. Before race day, write down what you expect to take at each major checkpoint. Include the distance to the next station, whether you have a drop bag, and the food or drink you intend to collect.

A simple checkpoint routine might be: refill bottles, take two or three minutes of food, check the next section, then leave. If you sit down without a clear reason, a short stop can become a long one. However, rushing through every station is equally unhelpful when you need calories, layers, or a proper reset.

Use drop bags to divide the race into manageable blocks. Label them by location and include backup choices rather than an entire pantry. A spare soft flask, familiar snacks, salt capsules if prescribed in your plan, and a warm drink sachet can be more valuable than extra products you have never tested.

Keep an emergency reserve for delays:

Crew members should know the plan without becoming nutrition police. Give them clear instructions such as “offer small savoury food every 45 minutes” or “ask about drinking at each stop.” A calm crew can help you notice missed fuelling, but you still need to listen to your stomach and adjust when necessary.

Rehearse the plan and manage late-race problems

The best nutrition strategy is built during long training sessions. Practise eating while climbing, descending, running, and walking. Test the exact gels, bottles, soft flasks, caffeine products, and solid foods you expect to use. A product that works during a two-hour run may not suit hour 15, so include at least some extended sessions.

Caffeine requires particular care. It can improve alertness late in the event, but too much may increase nausea, anxiety, heart rate, or sleep disruption. If you use caffeine, delay part of your planned intake until the night section and test the total amount in training. Coffee from an aid station can be useful, but its strength is unpredictable.

When your stomach begins to fail, reduce the size of each serving rather than abandoning food completely. Slow down, switch temporarily to water and mild carbohydrates, and consider whether heat, excessive fluid, or hard effort is contributing. Vomiting, confusion, severe headache, or an inability to keep fluids down requires medical attention from race staff.

After the event, record what happened while the details are fresh. Note approximate intake, the timing of nausea, weather, terrain, sleep, and which foods remained appealing. An unsuccessful race still provides valuable information if you can distinguish a menu problem from pacing, dehydration, insufficient recovery, or an unusually hot day.

A useful plan fits on one page: hourly carbohydrate range, drinking approach, electrolyte product, caffeine timing, checkpoint actions, and backup foods. Practise that plan until eating becomes an ordinary part of moving forward. On race day, start early, take small amounts consistently, adapt to the conditions, and use each aid station to protect the next section.