Taper week has a way of making runners second-guess everything. Your mileage drops, your legs feel strange, and suddenly every nutrition article you've ever skimmed starts screaming at you to overhaul your diet. Don't. The week before a race is not the time to experiment. It's the time to be boring, deliberate, and consistent.
Here's what the evidence actually supports, and what's just noise.
The Golden Rule: Don't Change What's Working
The single most damaging thing you can do in taper week is treat it like a fresh start. New protein powder, a different pre-run snack, a juice cleanse you read about online. Your gut has spent months adapting to whatever you've been feeding it during training. That relationship matters more in the final seven days than most runners appreciate.
Gastrointestinal distress is one of the most common reasons runners underperform on race day. Studies consistently show that 30 to 50 percent of endurance athletes experience GI symptoms during competition. Many of those cases trace back to something introduced in the days before the start line, not a problem with the race itself.
Stick to foods you've eaten regularly throughout your training block. If white rice, chicken, and bananas have been your staples, keep them. If you've been eating whole grain pasta before long runs, that's your pre-race dinner. Familiarity isn't boring. It's strategy.
Carbohydrate Loading: Timing Is Everything
Carbohydrate loading is real and it works. But the way most runners apply it is wrong. Many start eating aggressively high carbohydrate meals on Monday or Tuesday before a Sunday race, which isn't just unnecessary. It can leave you feeling bloated, sluggish, and heavier going into race day.
Glycogen supercompensation, the actual mechanism behind carb loading, happens efficiently within 48 to 72 hours. Research supports a loading window of two to three days, not a full week. And it's only meaningfully beneficial for events lasting longer than 90 minutes. If you're racing a 5K or 10K, aggressive carb loading won't move the needle on performance and may just make you uncomfortable.
For marathon and half-marathon runners, the approach is straightforward. Keep your carbohydrate intake at training levels for most of the week, then bump it up meaningfully in the final two to three days. Aim for roughly 10 to 12 grams of carbohydrate per kilogram of body weight per day during those loading days. Prioritize easy-to-digest sources: white rice, pasta, bread, bananas, oats, and potatoes work well for most runners because they're low in fiber and familiar to the gut.
What you don't want is a mountain of vegetables, legumes, or high-fiber grains in those final days. That's not to say produce is bad for you at other times. The parts of plants you typically discard, including the skins, stems, and seeds that most people throw away, are often the most nutritious. But the week before a race is not when you want to be maximizing fiber intake.
The 72-Hour Rule: Avoid New Foods, Supplements, and "Experiments"
The 72-hour window before your race is sacred territory. Nothing new enters the picture. No new supplements, no unfamiliar restaurant cuisine, no high-fiber experiment, no exotic pre-race ritual someone in your running group swears by.
This applies to supplements as much as food. If you haven't been using beetroot powder, sodium bicarbonate, or high-dose antioxidants throughout your training, now is not the time to start. These can cause GI distress, and the potential performance benefit from a single dose is not worth the risk of spending miles three through eight looking for a portable toilet.
Caffeine deserves its own note here. If you use it regularly during training, you can and should use it on race day. But the dosing matters. The relationship between caffeine, exercise performance, and cardiac risk is more nuanced than most runners realize. A dose that's effective and comfortable for training should be your race day reference point. Don't double it because it's race day.
Similarly, steer well clear of energy drinks in the final days. The data on energy drinks and cardiac risk in athletes continues to grow, and there's no performance case for introducing them if they haven't been part of your training nutrition.
Hydration: Your Most Underestimated Variable
Most runners spend months thinking about fuel and roughly 48 hours thinking about hydration. That ratio should be reversed, at least in race week.
Arriving at the start line well-hydrated is not something you can fix on race morning. It's built over the final two days. Research suggests that even mild dehydration of around two percent of body weight is enough to impair endurance performance meaningfully. Getting ahead of that starts on Friday if you're racing Sunday.
The goal isn't to drink obsessively or force excessive fluid intake. Hyponatremia, dangerously low sodium caused by overdrinking, is a real and serious risk in endurance racing. The goal is consistent, steady hydration across the final 48 hours. Urine color is a practical guide: pale yellow, not clear, not dark.
Electrolytes matter here too. Sodium helps your body retain the fluid you're taking in. If you've been using an electrolyte strategy during long runs, continue it in the days before the race. If you haven't, adding salt to meals and eating salty foods is a low-risk, effective approach. Just don't reach for a product you've never used before.
Keep Protein Consistent. Don't Let It Drop.
When training volume drops during taper, some runners instinctively reduce their protein intake along with it. The logic seems to make sense: you're doing less, so you need less. But this is one of the more common and costly taper mistakes.
Protein's job during taper week isn't to fuel workouts. It's to preserve the muscle you've spent months building, support tissue repair from accumulated training stress, and keep you in positive nitrogen balance heading into the race. Research on endurance athletes consistently supports maintaining protein intake at 1.6 to 2.0 grams per kilogram of body weight per day, even as mileage decreases.
Keep your usual protein sources in place. Eggs, chicken, fish, Greek yogurt, legumes, whatever you've been eating throughout training. Don't overthink portion sizes. Just don't cut them because your run schedule looks lighter.
Race Morning: Simple, Familiar, Timed Right
Race morning nutrition gets a disproportionate amount of attention relative to how much it actually matters compared to what you've done the days before. That said, it's still worth getting right.
Eat a familiar, carbohydrate-rich meal two to three hours before the start. This gives your body time to digest and top off glycogen without leaving you uncomfortable on the starting line. Oatmeal, toast with peanut butter, a bagel with banana. These aren't exciting, but they're reliable.
Don't skip breakfast because you're nervous. Pre-race anxiety can suppress appetite, but showing up fasted to a marathon is a decision you'll feel somewhere around mile 18. If nerves make solid food difficult, a smoothie, sports drink, or easily digestible alternative works fine as long as it's something your stomach already knows.
Sleep: The Nutrition Variable Nobody Talks About
Your final week of prep isn't just about food and fluid. Sleep quality directly affects how your body processes and uses the nutrition you're giving it. Carbohydrate storage, protein synthesis, cortisol regulation, and glucose control all depend on adequate rest. The research on irregular sleep and its downstream health effects is striking, and athletes are not exempt from those consequences.
Many runners sleep poorly the night before a race. That's normal and largely unavoidable. What matters more is the two or three nights before that. Prioritize sleep from Wednesday onward if you're racing on the weekend. Everything else you do with your nutrition in taper week works better when recovery is solid.
The Summary You Can Actually Use
- Keep your diet consistent for the first four to five days of taper week. No dramatic changes.
- Start carb loading 48 to 72 hours out, not at the beginning of the week. Only meaningful for events over 90 minutes.
- Avoid all new foods and supplements in the final 72 hours before the race.
- Hydrate consistently in the final 48 hours. Pale yellow urine is your target. Include electrolytes.
- Maintain protein intake at training levels throughout taper week. Don't let it drop with your mileage.
- Eat a familiar breakfast two to three hours before the start. Don't skip it.
- Prioritize sleep from midweek onward. Wednesday, Thursday, and Friday night matter more than Saturday.
Taper week is not a window for optimization. It's a window for protection. The fitness gains are locked in. Your job now is to arrive at the start line fueled, hydrated, rested, and free of any avoidable surprises. The simplest nutrition plan you can imagine is probably the right one.