Spring Race Nutrition: What Runners Get Wrong

Marathon registrations just hit a record high. Spring race season is here, and your Instagram feed is full of long run selfies and gel packet reviews. But here's the thing most training plans skip over entirely: what you eat in the 8 weeks before race day matters more than what you eat the morning of.

A 2024 meta-analysis in the British Journal of Sports Medicine found that runners who tracked their daily nutrition during training blocks reported 23% fewer bonking episodes on race day compared to those who winged it. That number surprised even the researchers.

Your Training Diet Isn't Your Normal Diet

Most recreational runners make the same mistake. They train like athletes but eat like they're not training at all. Or worse, they cut calories because they assume running burns enough to create a deficit automatically.

Key Takeaway: Training nutrition and regular nutrition are different things. Running 50+ km per week changes your carbohydrate, protein, and hydration needs substantially.

Here's what changes when you're in a training block: your carbohydrate needs jump to roughly 5-7 grams per kilogram of body weight per day, according to the American College of Sports Medicine. For a 70 kg runner, that's 350-490 grams of carbs daily. Most people eat around 200-250 grams without thinking about it.

Protein requirements also shift upward. Research from the International Society of Sports Nutrition suggests endurance athletes need 1.2-1.6 g/kg/day, not the standard 0.8 g/kg recommendation for sedentary adults. That extra protein supports muscle repair between sessions and helps prevent the gradual breakdown that accumulates over long training blocks.

The Carb-Loading Myth (Sort Of)

Everyone knows about carb-loading before a marathon. Fewer people know they're probably doing it wrong.

Traditional carb-loading protocols from the 1960s involved a depletion phase followed by a supercompensation phase. You'd eat almost no carbs for three days, then stuff yourself with pasta. Modern sports science has moved on. A 2019 study in the Journal of Applied Physiology showed that a simple 48-hour increase in carbohydrate intake (to about 10 g/kg/day) works just as well, without the miserable depletion phase.

Stat: Runners who gradually increase carbs over 48 hours before race day store roughly the same amount of muscle glycogen as those following the old depletion-loading protocol, according to research from Australian Catholic University.

The real trick isn't the loading itself. It's knowing your baseline. If you don't track what you normally eat, you have no idea whether you've actually increased your carb intake or just eaten more bread at dinner and called it a day.

Hydration: Stop Drinking So Much Water

This one catches people off guard. Over-hydration is a genuine risk during marathon training, and it sends runners to the hospital every spring.

Exercise-associated hyponatremia (EAH) happens when you drink so much water that your blood sodium levels drop dangerously low. A study published in the New England Journal of Medicine found that 13% of Boston Marathon finishers had hyponatremia. Most of them had been following the advice to "drink as much as possible."

The current recommendation from the International Marathon Medical Directors Association is simple: drink to thirst. Not on a schedule, not a fixed amount per hour. Just drink when you're thirsty.

Key Takeaway: Drinking to thirst is now the evidence-based recommendation for marathon hydration. Over-drinking water without electrolytes creates real medical risk.

Electrolytes matter more than volume. Sodium, potassium, and magnesium all leave your body through sweat. Replacing water without replacing electrolytes dilutes what's left. Sports drinks exist for a reason, and that reason is not marketing.

Race Week: What to Actually Do

The week before your race isn't the time for experiments. Every sports nutritionist will tell you the same thing: nothing new on race week.

Here's a practical timeline based on current guidelines:

7 days out: Maintain your normal training diet. Don't change anything yet.

3 days out: Begin increasing carbs to 8-10 g/kg/day. Reduce fiber intake slightly to avoid GI issues. Keep protein steady.

The night before: A carb-rich dinner you've eaten before. Rice, pasta, potatoes. Not the exotic Thai place you've been meaning to try.

Race morning: 1-4 g/kg of carbs, 2-4 hours before the start. Toast with jam, a banana, oatmeal. Whatever you've practiced during long runs.

Stat: A 2023 survey of 1,200 marathon runners found that 67% of those who experienced GI distress during a race had tried a new food or supplement on race day for the first time.

Tracking Makes the Invisible Visible

The consistent thread in all of this research is awareness. Runners who know their daily macro intake can adjust it intentionally. Runners who don't are guessing.

You don't need to weigh every grain of rice forever. But spending a few weeks tracking what you eat during a training block gives you data. Actual numbers instead of feelings. "I think I eat enough carbs" is different from "I eat 320 grams of carbs per day and need to bump it to 400."

Key Takeaway: Even short-term nutrition tracking during training blocks gives runners the data they need to fuel properly on race day. You can't adjust what you can't measure.

Whether you use an app, a spreadsheet, or a notebook, the act of recording what goes in changes your relationship with food during training. It stops being abstract and becomes a tool, like your running shoes or your watch.

FAQ

How many carbs should I eat per day during marathon training?

Sports science guidelines suggest 5-7 grams of carbohydrate per kilogram of body weight daily during heavy training. For a 70 kg runner, that translates to 350-490 grams per day. Track your intake for a week to see where you actually stand before making changes.

Is carb-loading before a marathon still recommended?

Yes, but the old depletion method is outdated. Modern research supports a simpler approach: increase carbohydrate intake to about 10 g/kg/day for the 48 hours before your race. No depletion phase needed. This achieves similar glycogen storage with less misery.

How much water should I drink during a marathon?

Drink to thirst, not on a fixed schedule. The International Marathon Medical Directors Association recommends against over-drinking, which can cause hyponatremia (dangerously low blood sodium). Include electrolytes, especially sodium, in your hydration strategy.

Should I take protein supplements during race training?

Endurance athletes may benefit from 1.2-1.6 g of protein per kilogram of body weight daily, according to the International Society of Sports Nutrition. Whether that comes from supplements or food doesn't matter much. What matters is hitting the target consistently across your training block.

What should I eat the morning of a race?

Aim for 1-4 grams of carbs per kilogram of body weight, eaten 2-4 hours before the start. Stick to foods you've tested during training. Common choices include toast with jam, oatmeal, bananas, or rice cakes. Never try something new on race morning.

— Emma