Why Carboloading is a Mistake (and What to Do Instead)

By Ben Connelly

When I was in high school, my teammates and I used to routinely gather the night before a 5k to eat enormous quantities of food – usually pasta, pizza, bread, cookies, and brownies. At the time, we actually thought this would improve our times. Luckily, we were at an age where our digestion and metabolism could keep up, and most of us raced fine the next morning.

While most runners probably understand why carboloading the night before a 5k is unhelpful at best, many still fall prey to the misconception that carboloading will improve their marathon times. It will not. Today, I am going to explore why.

The Theory of Carboloading:

The theory behind carboloading is that runners need to store up large amounts of carbs which they will then burn off during a race. It should be obvious that, at distances as short as the 5k, this is untrue. Many runners will be lucky to burn off the calories in a single plain bagel while running a 5k, let alone a bagel with peanut butter on it. 

But a marathon burns far more calories than a 5k. And marathoners need to ensure their glycogen stores do not run low in order to avoid hitting the wall. So, carboloading should help, right?

There are a couple reasons why carboloading will not help your marathon time, and a couple of reasons why it might be counterproductive.

Why Carboloading Does Not Work:

Even if you drink vast quantities of water, there is a limit to how much glycogen you can store in your muscles. If you gorge yourself on a carbohydrate-rich meal (likely high in fat, too), most of the excess calories you consume will be stored as fat. Unless you are already at 4% bodyfat, more fat is only likely to slow your race, not help it. 

The process of storing glycogen in your muscles takes time. A single meal the night before your race is not going to cut it. In fact, that might be too late to help at all. The next best hope for the carboloading theory is that some of the carbs will still be undigested by the time you start the race. But that brings us to why carboloading is counterproductive.

Why Carboloading is Counterproductive:

If you have large quantities of undigested food in your stomach at the start of your race, you risk gastrointestinal mishaps: from vomiting to bathroom visits. Even worse, most of the foods runners gorge themselves on the night before races are – by themselves – culprits for gastrointestinal distress during races. Fettucine alfredo, pizza, beer, blondies, cookies, buttered bread, fries, garlic knots, etc.

Indulge post-race, not the night before. 

Finally, eating a very large, hard-to-digest meal any night of the week can cause stomach troubles and difficulty sleeping. If you stuff yourself the night before a race, you are definitely not helping your race the next day. 

What to Do Instead:

The night before your race, you want to eat a small, easy-to-digest meal of primarily carbohydrates and protein. Plain rice, with nothing on it, plain chicken, and some very-digestible vegetable. Or plain pasta (without sauce or butter), and maybe some chicken and cooked spinach. 

To build up glycogen stores, you want to prepare in the weeks before your race by consuming more of your calories from carbohydrates – while cutting total calories as you taper. The day and night before your race, your main goal is just to avoid doing anything that might harm your race, not to try to catch up on your carbs. 

If a food or beverage sounds like it would be “unhealthy” any normal night, you definitely want to avoid it the night before your race. The night before your marathon, eat enough so that you do not go to bed hungry, but not so much that you feel full.


No Replies to "Why Carboloading is a Mistake (and What to Do Instead)"