Race day is circled on the calendar, your training block is wrapping up, and now comes a phase that a surprising number of OCR athletes get completely wrong: race week nutrition. What you eat in the five days leading up to the start line doesn’t just top off your tank — it can meaningfully affect your grip strength in the final kilometer, how your stomach handles the mud-water you’ll inevitably swallow, and whether you cross the finish line feeling strong or empty.
This is not about race-day fueling (what you eat the morning of and carry on course) or post-race recovery. This is the window before all of that — the quiet five days where smart eating builds the platform everything else runs on.
Understand What You’re Actually Building
Your muscles and liver store carbohydrate as glycogen — the primary fuel for everything from burpee penalties to the last rope climb. A well-fueled athlete can store roughly 400–600 grams of glycogen total. A depleted one might carry half that. That difference shows up around the two-thirds mark of a Spartan Super or Beast, when legs start feeling like wet concrete.
Race week nutrition has three goals: maximize glycogen stores for the demands of your race distance, keep the gut calm and predictable, and stay properly hydrated so your body can actually use what you’re feeding it. These goals work together — and violating one usually undermines the others.
Days 5–3 Out: Build the Base
Three to five days before race day, start gently shifting your plate. You don’t need to abandon vegetables or protein — just nudge the carbohydrate percentage upward. Aim for easily digestible sources: white rice, pasta, bread, oats, potatoes, and bananas. These digest cleanly and convert to glycogen without putting a lot of fermentation stress on your gut.
Protein stays at its normal level — roughly 0.7–1g per pound of bodyweight — to support muscle repair after your final training sessions. Fats can stay moderate, but don’t add extra fat in the name of ‘energy density.’ Fat slows gastric emptying, which is the last thing you want heading into race week.
Keep vegetables in the picture at this stage, but begin steering away from high-fiber cruciferous options (broccoli, cabbage, Brussels sprouts) and legumes. They’re excellent for general health but generate gas and digestive load that doesn’t serve you in the days before a race. Swap in lower-fiber alternatives: cooked carrots, zucchini, spinach, cucumber.
Days 2–1 Out: The Carb Load Window
The two days before race day are the core carb-loading window. Research consistently supports carbohydrate loading in the 24–48 hours before endurance events lasting more than 90 minutes — which describes any Spartan Super (8–10+ miles), Beast (13+ miles), or ultra-distance OCR. For shorter sprints (3–5 miles), a full carb load is less critical, but topping off glycogen stores is still worthwhile.
For a Beast or ultra: target 8–12 grams of carbohydrate per kilogram of bodyweight per day across these two days. For a 70kg (154lb) athlete, that’s 560–840g of carbs daily — considerably more than usual. Spread it across four to five meals to avoid feeling stuffed. White rice, pasta with a light sauce, bread, bagels, pancakes, bananas, and sports drinks all count. Avoid anything unfamiliar — race week is absolutely not the time to try a new cuisine or trendy superfood.
For a Sprint (under 5 miles): a moderate carb increase over these two days is sufficient. Eat slightly larger portions of your usual carb sources and make sure your last meal before race morning is carb-forward. You don’t need to engineer a full glycogen-loading protocol for a 45-minute race.
Hydration: Start Earlier Than You Think
Most athletes treat hydration as a race-morning task. That’s late. Genuine cellular hydration — fluid inside the muscle cells, not just water sloshing in your stomach — requires 48–72 hours of consistent intake. By the time you’re thirsty, you’re already behind.
In the five days before your race, aim for at least half your bodyweight in ounces of water daily (a 180lb athlete targets 90oz minimum). Add an electrolyte source — sodium is particularly important — especially if you’re sweating through final tune-up workouts or live in a hot climate. Low-sodium sports drinks, electrolyte tablets, or even salted food work fine. Urine color is an honest barometer: pale yellow is the target; dark yellow means drink more; clear means you’ve overdone it and flushed electrolytes.
Back off alcohol for the full five days if you can. Alcohol is a diuretic, disrupts sleep quality, and impairs glycogen synthesis. Race week is a short window — the beer will taste better after the finish line anyway.
Foods to Avoid in Race Week
A partial list of things that have derailed race-week nutrition with uncomfortable frequency:
High-fiber foods: Beans, lentils, raw brassicas, and whole-grain breads with lots of seeds. Great for general health; terrible for pre-race gut stability. Taper the fiber as the race approaches.
Spicy or heavily seasoned meals: New or intense spices can irritate the GI tract and cause issues during the race itself. Stick to familiar, mild flavors.
Fatty and fried foods: Slows digestion, can cause nausea during high-intensity efforts, and displaces carbs you need. This includes protein sources like fatty cuts of red meat or fried chicken the night before a race.
Excess sugar and refined sweets: A small amount of sugar is fine and even useful for quick glycogen replenishment. A binge of candy or pastries can cause blood sugar swings and GI distress.
Unfamiliar foods: Anything your gut hasn’t processed before. Race week has a ‘novelty budget’ of zero.
Adjusting by Race Distance
Sprint (3–5 miles, 20–45 obstacles): Keep eating normally through days 5–3. In the final two days, increase carb portions modestly and make your pre-race dinner carb-heavy. Full glycogen loading is overkill, but don’t show up depleted. Focus more on gut comfort than loading volume.
Super (8–10 miles, 25+ obstacles): Begin carb-shifting around day 4. Use the two-day loading window with a target around 7–9g of carbs per kilogram bodyweight. Hydration becomes critical here — the race will push 90–150 minutes for most athletes. Electrolyte intake during the loading window is worth prioritizing.
Beast / Ultra (13–30+ miles): Treat this like a marathon or half-ironman prep. Full carb loading protocol from days 2–1 (8–12g/kg). The glycogen stores you build in this window are what keep you moving when the course gets technical in the final third. Don’t skip the electrolytes and don’t skimp on sleep — recovery during race week is part of the fueling equation.
The Practical Race Week Plate
If you want a simple template to follow without overthinking the macros:
Days 5–3: Normal balanced meals, slightly larger carb portions. Reduce high-fiber vegetables. Hydrate consistently. Avoid alcohol.
Days 2–1: Carbs front and center at every meal. Familiar, easily digestible foods only. Electrolytes in water or drinks. Light protein (chicken, eggs, fish), minimal added fat. No alcohol. Early bedtime if possible.
Race Eve: A satisfying but not excessive carb-forward dinner (pasta, rice bowls, pancakes — whatever your gut knows well). Eat by 7–8pm if your race is an early morning start. Hydrate through the evening; don’t chug water right before bed.
A Note on Individual Variation
The strategies above reflect current sport nutrition consensus for endurance and obstacle racing, but everyone’s gut, training history, and metabolism responds differently. Athletes with IBS, food sensitivities, or specific medical conditions should work with a registered dietitian or sports nutritionist to adapt these principles to their situation. The guidance here is educational, not clinical — if something consistently causes you GI distress, trust your body and find what works for you.
The five days before your race aren’t glamorous. There are no secret supplements, no magic timing tricks. It’s mostly just eating well, sleeping well, and staying out of your own way. Do that consistently and you’ll show up to the start line as loaded and ready as your training will allow.