What to Eat Before a Run, According to Experts

When it comes to what to eat before a run, successfully fueling before lacing up your trainers requires careful consideration. From short sprint work to hours-long efforts, every run is different, meaning every breakfast, snack, and even every drink you take needs planning in advance.

Get it wrong and you’re at risk of feeling too sluggish, or burning out too soon. Here, our experts serve up a nutritional plan to help you stay the course.

What do our bodies actually need before a run?

“The primary goal is to top up your available energy,” says Emma Kirk-Odunubi, a marathoner and sports scientist. The key source of energy is muscle glycogen, i.e. the energy we get from carbs and store in our muscles. “Glycogen is the rocket fuel your body taps into for moderate-to-high-intensity running,” says Kirk-Odunubi.

If you’re running on an empty stomach, or with low glycogen stores—say after a heavy workout the night before—you’ll be relying on fat for fuel, which is a slow process. “Fat oxidation takes time,” says Kirk-Odunubi, “It can’t support high running speeds very well, so you might feel sluggish or heavy-legged.”

This, of course, is when your run quality drops and any hope of personal bests goes out the window. Eating carbs before running means your muscle cells become more primed to take up and store glucose as glycogen, while reducing your body’s need to burn glycogen early, which can be a performance advantage in runs over 45 minutes.

“The most important thing is that your muscles and brain get a quick-access energy source so you can hit your paces without digging too deep into reserves,” says Kirk-Odunubi.

What about hydration?

Alistair Brownlee, double Olympic gold medalist, triathlete, and co-founder of truefuels knows all about hydration. He says electrolytes and sodium in particular are crucial to supporting performance.

“Water is important because even mild dehydration (-2% body weight) can impair aerobic performance, increase heart rate, and elevate perceived effort,” he says.

It isn’t about downing as much water as possible pre-run. Instead, aim for the “sweet spot” of 500ml taken 90-30 minutes before exercise, depending on heat conditions. This allows time for kidney regulation, and also aids in glycogen storage from your pre-race carbs.

As for sodium, Brownlee calls it “the most critical electrolyte lost in sweat.” It’s essential for fluid retention, reducing cramps, and nerve transmission, which improves coordination and reaction time.