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 targets

Fluid target:

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

Carbohydrate target:

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

Step 2: Choose 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 on an easy 10 km? Test it glycogen-depleted and hot.
• GI tolerance. Some athletes tolerate maltodextrin-based gels fine; others do better with more natural carbohydrate sources.
• Caffeine timing. Caffeine gels (typically 75 mg caffeine) need to be timed correctly — most athletes save them for the second half.
• Product availability on course. If the race provides a brand you haven't trained with, decide now: carry your own or adapt. Carrying your own is safer.

Step 3: Build your race-day schedule

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 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 use a laminated card. The point is to not make decisions mid-race when cognitive function is degraded.

Step 4: The pre-race 48 hours

48 hours out: If carbohydrate loading, increase intake to 8–10 g/kg body weight daily. Focus on easily digestible sources — white rice, white pasta, white bread, bananas, sports drinks. Avoid anything new, high-fibre foods, large amounts of dairy, or alcohol.

Race morning: Eat 2–3 hours before the start. Target 1–4 g of carbohydrate per kg body weight. Familiar foods only. 500 ml of fluid with breakfast; small sips up to the start. Caffeine (3–6 mg/kg) 30–60 minutes before start if you use it.

The goal is to top up liver glycogen — which depletes overnight — without loading your gut with undigested food.

What to do when things go wrong

GI distress mid-race: Back off pace slightly. Switch to liquid carbohydrates (sports drink at aid stations) if you can't tolerate gels. Avoid fructose-heavy products. Sip fluid in small amounts rather than large volumes.

Hitting the wall: If you're bonking past mile 18, you're in damage-limitation mode. Keep taking carbohydrates — the situation gets worse without them. Slow down enough that gut function can keep pace with intake.

Hotter than expected: Increase fluid at every aid station. Add electrolyte tablets 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 following your race nutrition plan exactly. You're testing whether you can absorb what you plan to consume at race intensity, whether your products hold up under fatigue, and whether your timing feels natural.

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, target event, and 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 based on predicted conditions.

---

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