How to build a race-day nutrition plan from scratch

Most athletes start thinking seriously about race-day nutrition about two weeks before their event. By then, it's too late to train your gut, too late to discover you can't tolerate a particular gel brand, and too late to know whether your sweat rate in race conditions will match your training estimate.

Building a race-day nutrition plan is a training project, not a pre-race checklist. This guide covers what you actually need to do, in the right order.

What a race-day nutrition plan consists of

A complete plan has three components:

1. Pre-race nutrition — what you eat and drink in the 24–48 hours before the start, and specifically on race morning.

2. In-race fueling — your hydration and carbohydrate schedule during the event, mapped to aid stations and kilometre markers.

3. Contingency decisions — what to do if your plan breaks down (GI distress, hotter or colder than expected, missing an aid station).

Most advice focuses exclusively on in-race fueling. The pre-race component is equally important and more controllable.

Step 1: Calculate your carbohydrate and fluid targets

Before you can build a plan, you need your targets.

Fluid target:

• Measure your sweat rate across 3–5 training sessions at different intensities (see our guide on sweat rate)
• Adjust upward by 15–25% for warmer-than-training conditions
• Set a per-hour target, then break it down by aid station

Carbohydrate target:

• Use your race pace and body weight as inputs
• Under 2:30: target 80–90g/hour from a glucose+fructose blend
• 2:30–4:00: target 60–80g/hour
• Over 4:00: target 45–65g/hour
• These ranges assume you've trained your gut at these levels

Step 2: Choose your products — and commit early

Test your products in training. Not once. Across multiple long runs, in conditions as close as possible to race day.

What you're testing:

• Palatability at race intensity. Does the gel taste fine in an easy 10km? Great. Does it still work on a long run when you're glycogen-depleted and hot? Test that.
• GI tolerance. Some athletes tolerate maltodextrin-based gels fine; others do better with more natural carbohydrate sources. There's no universal answer.
• Caffeine timing. Caffeine-containing gels (typically 75mg caffeine) are effective but need to be timed correctly. Most athletes save them for the second half of a race.
• Product availability on course. If the race provides SiS gels at aid stations and you've been training with Maurten, you need to decide: carry your own, or adapt. Carrying your own is safer.

Step 3: Build your race-day schedule

Map your fueling targets to your expected race timeline:

1. Note every aid station location on the course
2. Calculate expected arrival times based on your target pace
3. Assign a fluid target to each aid station stop
4. Assign gel timing between aid stations (so you can wash each gel down with fluid)
5. Add contingency: if you miss an aid station, what's the fallback?

Write this down. Some athletes write it on their arm. Others print a small laminated card. The point is not to have to make decisions mid-race when your cognitive function is degraded.

Step 4: The pre-race 48 hours

48 hours out:

• If carbohydrate loading: increase carbohydrate intake to 8–10g per kg body weight daily for 2–3 days before the race. Focus on easily digestible sources.
• Avoid anything new, particularly high-fibre foods, large amounts of dairy, or alcohol.
• Hydrate normally — don't drink excessively.

Race morning:

• Eat 2–3 hours before the start
• Target 1–4g of carbohydrate per kg body weight
• Familiar foods. No experiments.
• 500ml of fluid with breakfast; small sips up to the start
• Some athletes use 3–6mg/kg bodyweight of caffeine 30–60 minutes before the start

The goal of race morning nutrition is to top up liver glycogen (which depletes overnight) without loading your gut with food that hasn't had time to be digested.

What to do when things go wrong

GI distress mid-race:

• Back off pace slightly — high intensity reduces gut blood flow and makes things worse
• Switch to liquid carbohydrates (sports drink at aid stations) if you can't tolerate gels
• Avoid fructose-heavy products
• Keep sipping fluid in small amounts rather than taking large volumes

Hitting the wall:

• If you're bonking and you're past mile 18, you're in damage-limitation mode
• Keep taking carbohydrates — the situation will get worse without them, not better
• Slow down enough that gut function can keep pace with your intake

Hotter than expected:

• Increase fluid intake at every aid station
• Consider electrolyte tablets or capsules if available
• Accept a pace adjustment — dehydration compounds with effort

Testing the plan before race day

Run at least two long runs (90+ minutes) at close to race pace where you follow your race nutrition plan exactly. You're testing:

• Whether you can absorb what you plan to consume at race intensity
• Whether your product choices hold up under fatigue
• Whether your timing feels natural and executable

These sessions are not optional. Race day should not be the first time you've attempted race nutrition.

Sweatr's race planning wizard takes your training data, your target event, and your measured sweat rate — and builds a specific, timed plan with the products you've told it you're using. It adapts as your training load changes in the weeks before your event, and gives you a final plan the night before your race based on predicted conditions.

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For triathlon-specific fueling across swim, bike, and run legs, see our dedicated triathlon nutrition guide.