Whether you’re racing or training, what you eat before your run has a big impact on both your performance and recovery. It’s important to fuel your body properly before and during a run if you want to get the most out of it, but it’s also essential to eat in such a way as to ensure that you don’t overdo it and end up with a calorie surplus that would cause you to gain weight.
It’s most important to plan what you eat before a run when you’re covering longer distances, or working on endurance runs of an hour or more, but for shorter runs, a quick snack like a banana should be fine to give you a boost.
Where You Get Energy for Runs
Your body takes on fuel from two main sources:
Generally carbohydrates are broken down into two groups based on how quickly they are broken down into glucose and released into the bloodstream. These are called Low and High GI foods. Low Glycaemic Index foods are broken down slowly by the body, and are generally best eaten well before a run. Low GI foods are more complex carbohydrates include things like pasta and rice. They can be quite filling, and will provide lots of energy slowly.
High GI foods are better just before a run. These include simpler carbs such as sugar – although it’s best to avoid refined sugar products like chocolate unless you’re confident you can burn all the calories. Honey on toast is a good snack that gives you a good mix of low and high GI carbs. As do sports drinks which are designed specifically for different activities.
In most cases your body will burn the high GI sugars at the start of your run, while insulin is released to free up the more complex low GI carbohydrates and fats later in the run to help you maintain a healthy level of blood sugar and maintain performance at consistent levels.