By Dr. Lauren Helf, DC · Updated August 2026

Running a marathon takes preparation on every level — physical and mental. Your body has to be ready to carry you through 26.2 miles, and your mind has to get you past the walls that show up along the way. Training builds both, but there’s one piece runners often underestimate: fueling. What you eat and drink in the weeks and days before a race has a direct effect on how you feel at mile 20. Getting it right is one of the most reliable ways to run your best when it counts.

If you’ve put in the work — the long runs, the hard workouts, the attention to form and recovery — the final stretch is less about doing more and more about fueling smart. As the race approaches, your mind may try to convince you that you haven’t done enough. Try not to obsess over the details. Nutrition is the lever that’s still fully in your control, so let’s use it well.

Start With Hydration

Your body is roughly 60% water, so hydration matters long before the starting line. You lose water throughout the day through sweat and normal activity, and it adds up quickly during heavy training. A reasonable daily target for most people is about eight 8-ounce cups of water — roughly two liters, or half a gallon — adjusted up when you’re training hard or the weather is warm.

Around your runs, a simple rhythm helps. Drink about two cups of water or a sports drink a couple of hours before you train, which gives your body time to process it and lets you empty your bladder before you start. Top off with another 5 to 10 ounces just before you head out.

Rehydrating afterward is just as important. A common guideline is about 24 ounces of fluid for every pound lost during a run. If you’d rather not weigh yourself each time, watch the color of your urine instead — you’re aiming for pale yellow rather than clear or dark.

Carbohydrate Loading

Carbohydrate loading is a well-established strategy endurance athletes use to maximize the glycogen — stored energy — in their muscles. The concept is straightforward: in the days before a race, you take in extra carbohydrates so your muscles have more fuel to draw on when you need it most.

Protein gets a lot of attention, but carbohydrates are what actually power sustained physical activity. That can sound backward, since carbs are often treated as something to avoid. For a marathoner, though, getting enough of them is essential — especially on long training days and in the final week of preparation.

How Do You Carb Load?

Carb loading happens in the final week. Roughly three to four days before the race, many runners increase their carb intake so carbohydrates make up the majority of their daily calories, and ease back on higher-fat foods to make room. Every runner responds a little differently, so it’s worth learning what balance works for your body before race week arrives.

The second half of carb loading is often overlooked: scale back your training at the same time. Take a true rest day the day before the race, and if you need to move at all, keep it to light stretching. Combining more carbohydrates with less exertion is what allows your glycogen stores to fill — and that translates to a stronger run when it matters.

Keep Your Overall Nutrition Balanced

While you’re focused on carbohydrates, don’t let the rest of your nutrition slip. Lean on whole, plant-forward foods rich in the vitamins and minerals your body relies on. Where you can, choose protein from beans, legumes, and lean poultry, and go easier on red meat and pork. Dairy is another one many runners pull back on in the final stretch, particularly the day before the race.

Above all, stay consistent and test your plan in advance. Experiment with your pre-race meal during training so there are no surprises on race morning. The classic oatmeal and nut butter works well for some runners and not at all for others — the time to find that out is well before the starting line, not on it.

Where Supplements Can Help

Sometimes diet alone doesn’t cover everything, and targeted supplements can help fill the gaps. Always talk with your provider before adding them, so they fit safely with the rest of your routine and any medications you take. With that in mind, here are a few runners commonly ask about.

Fish Oil

Hard, sustained training asks a lot of your body, including your heart. Fish oil is popular among endurance athletes because it may help support heart health and healthy blood pressure, and its anti-inflammatory properties may support recovery between demanding efforts.

Magnesium

Magnesium is one of the most important minerals in the diet, playing a role in energy production and muscle contraction. Long, demanding endurance efforts can deplete it, so runners often top up. It also supports strong bones and muscles, cardiovascular health, and healthy nervous system function.

Vitamins C and E

Both are antioxidants that can support long-distance runners. Vitamin C is best known for supporting the immune system, but it also helps counter the oxidative stress that comes with heavy training. Vitamin E works along similar lines and supports heart and cardiovascular health.

Zinc

A little of this mineral goes a long way. Zinc supports many of the enzymes involved in energy metabolism, and endurance athletes often lose some through exercise, so replenishing it helps. It also supports a healthy immune system — welcome insurance when you’re trying not to catch a cold days before the race.

Nutrition Is Only Part of the Picture

Fueling is just one piece of preparing for a marathon. Your training, your mental game, and your recovery all matter just as much, and they work best together. Chiropractic care fits naturally into that whole-body approach — supporting your movement, easing the strain of heavy training, and helping your body hold up under the demands you’re placing on it. Our post on preventing running injuries with chiropractic care is a good companion read.

If you’re training in Cranberry Township and want your body as ready as your mind, make an appointment with us. We’ll talk through your training routine and where you’re feeling the strain during your first visit, and build a plan to help you reach the finish line feeling strong.