What Foods to Avoid the Day Before a Long Run or a Race

First things first

Don’t make too many changes! Probably the absolute best thing you could do is to stick to your normal diet.

It’s too late for carbohydrate-loading, and eating 20 different vegetables the night before isn’t suddenly going to transform you into a vision of health.

That doesn’t mean we can’t make a couple of changes to help you, but these changes are more about avoiding gastrointestinal distress than giving you an incredible advantage over your nutritionally-challenged competitors.

What conditions do we want to create?

When planning your meals, you should be thinking about what outcome you want.

  • You want a lot of energy before a race, which means that you’ll want a really good night’s sleep beforehand. This will reduce fatigue, clear your mind, and help you to run faster.

    A 2011 study on Collegiate Basketballers by Mah et al found that sleeping more than usual (8 hours +) led to improved performance and mood compared to regular or bad sleep.

  • You also don’t want to suffer from any gastrointestinal discomfort during a run. Trust us, there is absolutely nothing worse than finding out that last night’s meal disagreed with you halfway through a marathon!
  • Finally, you want your body to be able to devote as much energy as possible to the run. This means that you don’t want your body digesting last night’s massive carbohydrate fest. You need a good balance between eating for performance and not over-eating.

Foods to avoid #1 Caffeine

While caffeine has a number of benefits to performance, it can keep you alert for a long time after consumption. A cup of coffee can affect sleep for 6-8 hours after it has been consumed (depending on the tolerance of the person drinking it).

Try to avoid caffeine the day before your race. This will ensure that you have the best chance of a good night’s sleep. You can of course take caffeine the morning after, and even as a pre-run drink (though this does depend on the length of the race – shorter the better).

Foods to avoid #2 Fatty Foods

High fat foods are not necessarily unhealthy, and many people are starting to turn to higher fat diets such as keto. But the night before a big race you want to limit them.

There are two reasons for this

  1. High fat foods take a long time to digest, which can affect performance and
  2. they can also cause upset stomachs, not great during a run!

Foods to avoid #3 High-fibre foods

Fibre has many benefits and most Western diets could benefit from including more fibre. But as with high-fat foods, high-fibre foods can cause digestive issues.

Fibre can also dehydrate you, if you increase your fibre intake dramatically without also increasing your water intake the fibre can dehydrate you as it gets digested. As you’ll be exercising too, the dangers of dehydration are even higher than usual.

Foods to avoid #4 Carbohydrate Overconsumption

You absolutely need carbohydrates the night before, but you don’t want to overdo things. Not only will too many carbs affect your digestion, it will also often cause you to consume too much fibre (see above).

Carb overload will also affect sleep, remember that doubling your carb intake is basically doubling your calorie intake for the day. Your body will take longer to digest it. This will affect sleep.

Foods to avoid #5 Anything New

The day before a race is not the time to experiment with your diet, if you’ve never eaten vegetarian lasagne before, or mackerel, then don’t start tonight. Be boring, stay safe, eat something that you eat all the time, which your body can easily handle.

Final Thoughts

Your breakfast and lunch the day before can be whatever you normally have, they are unlikely to affect your run at all as they are so far away from it. Just don’t eat anything crazy! Your evening meal is important though.

You can increase the amount of carbohydrates slightly, but don’t go overboard.

You can still have some fat but try to limit it slightly. Make sure that fat does not contribute more than 15% of your meal (use a calorie/macro counting app such as myfitnesspal to check).

Protein should be around 35% of the meal, which should be your normal amount.

Avoid caffeine after midday, and don’t overdo it with the water or sports drinks. Just drink water if you’re thirsty. Obviously stay away from alcohol, that can be a post-race vice!

Carbohydrate Loading: A Quick Word

At the beginning of this article we made a brief mention of why you should avoid carbohydrate loading the night before a race. This may appear to fly in the face of conventional wisdom so we thought we’d give a very brief explanation.

Carbohydrate loading is a strategy used by runners to increase their glycogen stores. Glycogen is basically stored energy that you get from carbohydrates.
Some studies have indicated that performing a high intensity workout (2 minutes of all-out cycling) then consuming a lot of carbs can lead to a 90% increase in stored glycogen.

There are other methods, including a three-day carb load and the traditional seven-day carb load. (Please see our article on pre-race nutrition for more info on carbo-loading)

As it does appear to work why are we advising against it? While there are benefits to carb loading, there are also drawbacks. Get it wrong and your entire race is ruined (think Paula Radcliffe having to go to the toilet during the marathon), and for MOST runners, the potential side-effects outweigh the benefits.

If you want to carbohydrate load then we would recommend experimenting with it while training (along a course with adequate facilities if you get our meaning). But ask yourself what you really want out of it.

There are a lot of ways to shave off seconds from your time, but not all of them are practical. Altitude training, hiring a nutritionist, biomechanical tests on your running gait etc …

Most people run for enjoyment, and over the years they try out new methods. If you’re just starting then try to keep your diet as normal as possible, you can experiment further down the line.




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