#5. How to fuel for your Half Marathon

You'll be shocked at how much you actually need to eat to perform optimally.

Welcome to race season!

I want to preface this post by saying I am not a running expert, nor would I even necessarily call myself a ‘runner’ at all. I run occasionally for leisure, for my physical and mental health, and for some good old fashioned cardiovascular training. I am however a nutritionist, and I’m fascinated by strategic sports nutrition and how eating and fuelling properly can help enhance our performance.

The first half marathon I ever ran felt brutally hard. Granted, I was young and naive (I think I was 19) and thought that because I was relatively fit, it would be no problem. I did not train or fuel properly for the race, and I definitely felt the effects of that. I finished around the 2 hour mark, but I was exhausted and frustrated because I knew I could do better.

The next 4 half marathons I ran were a steady progression of improvement. I’ve basically done one each year since 2018. I ran the next one in 1:48, then 1:45, 1:42 and most recently 1:35 at the Toronto Scotia Bank Half Marathon. Each time, I feel like I nail the nutritional plan a bit better!

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Day Before / Race Day Nutrition

During a half or full marathon you burn both glycogen and fat. But the latter is not as efficient, which means your body has to work harder to convert it into fuel. Carbs are the primary fuel burned during physical activity. Before your race, it is best to eat food that is rich in carbs and moderate to low in protein and fat. Too much fat, protein and fibre can cause digestive distress or discomfort while running. In the hours and minutes before your race, you want to fuel your body with carbohydrate rich foods.

Don’t overdo it on meats, dairy, cream sauces, oils or nuts in the hours, and even days before your race. Instead, you’ll want to make sure that you are eating carbs that are easily digestible. The body is more efficient and quicker at storing simple carbs as glycogen compared to complex carbs. So while yes, complex carbs are healthy and what you want to eat on a regular diet, opting for the simple, white stuff is actually a better race strategy.

Harder to break down carbs: leafy greens, beans, legumes, lentils, steel cut oats (rolled or quick/instant is MUCH easier to breakdown). Similarly, brown rice and whole wheat are take longer to break down than white flours and rice.

Easily digested carbs: bananas, dates, berries, smoothies, yams, potatoes, butternut squash, and simple grains like white rice, white grains, sourdough, oatmeal, homemade granola.

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More on Carb Loading

Carb loading is a nutritional strategy to increase exercise performance based on the idea that increasing the carbs you eat will top up your glycogen stores. The idea that eating more carbohydrates than normal, while at the same time not burning through them by tapering our exercise, is well researched and will increase the glycogen stored in your body above its normal amount.

3 days before your race should be the last time you run. In those 3 days leading up to your race, your diet should consist of 70% carbohydrates. Your body may store water alongside the carbs leading to a bit of weight gain or bloating; this is normal and not to be feared.

Carb intake can range from 3 - 5.5 g per pound of body weight. Make sure you are only increasing your carb intake, not fat, and be weary not to consume too much fibre.

This strategy is only appropriate for exercise lasting more than 90 minutes.

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Ergogenic Aids

1. Fat Loading: to be implemented 8-13 days prior. By eating 65-70% of your daily calories as fat for 5-10 days, you train your body to burn more fatty acids for fuel. This benefits you on race day by conserving glycogen stores.

2. Carb Loading: to be implemented 1-3 days prior to race day. By eating 3 - 5.5 grams of carbs per pound of body weight for 3 days prior to your race, you’ll ensure your glycogen stores are completely full as you begin racing, which can enhance your performance by 2-3% or more.

3. Beetroot Juice: to be implemented 2 - 2.5 hours prior to race. Research shows that drinking 500 ml of beet juice 2 - 2.5 hours before running can results in up to 3% performance enhancement. The inorganic nitrates in beet juice are converted by our bodies into nitrite than nitric oxide, which then positively affects blood flow, muscle contraction and neurotransmission.

4. Caffeine: to be implemented 60 - 90 minutes prior to race. Anywhere from 2-7% performance enhancement. Additionally, this recent study shows that caffeine intake 30 minutes prior to exercise burns more fat.

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More Specifically

When Should We Eat?
2 to 4 hours pre-race, ideally around the 3 hour mark. It is important to eat enough in the morning, as our liver is about 50% depleted of glycogen simply from overnight fasting. We pull from our liver and muscle glycogen stores for energy while running.

How Much Should We Eat?
When eating 3 to 4 hours prior, you ideally want to be eating 2 - 2.5 grams of carb per kg of body weight. Most people are shocked to hear how much they actually need to eat for optimal performance and a bit hesitant to eat so much. But it’s amazing what filling up those glycogen stores can do.

How Much Should We Eat During The Race?
90 minutes or more: 30 - 60 grams of carbs per hour. Most gels provide 25 grams of carbohydrate, so taking 1-2 gel packs during a half marathon is best practice.

What About Hydration?
Every time you consume gels, chews or real food, you need to wash it down with water. Drink to thirst.

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So, What Should Race Day Look Like?

I have a superstitious routine for my pre-race breakfast. I’ve done the same thing for the last few races and I swear by it.

First of all, don’t stuff yourself at dinner the night before the race. Dinner should be relatively small, but carb-heavy. You want to wake up race day hungry—not full from the night before. Eat an earlier dinner so that you have lots of time to digest properly.

The Toronto Waterfront half marathon starts at 8:45 am.

I’m planning on waking up at about 5:45 am to start prepping my oats. I am aiming for 2 - 2.5 g of carbs per kg of body weight before my race:
123 lb = about 55 kg.
2 - 2.5 x 55 = 110 - 137.5 grams of carbs

I’ll (attempt to) eat 1 cup of quick oats (~ 54 g of carbs) with 1 tbsp of maple syrup (~ 13 g of carbs) and 1/2 cup of mixed berries (~9 g of carbs). I also like to add a bit of peanut butter (1 tbsp has 3 g of carbs) so that my blood sugar doesn't spike too high. We’re at 79 g of carbs so far.

I’ll have coffee #1 with my oats.

At around 6:45 am, I will start drinking 500 ml of beetroot juice (48 g of carbs). I’ll aim to finish this by 7:30 am. 

At 7:30 am, I’ll have my second and final coffee.

At 8:30, I’ll have a date (~6 g of carbs). This puts me at 133 g of carbs. Usually, I can’t finish all this food so this is the the goal, but anything above 110 g of carbs will do.

8:45 am, I start to run. 

Instead of gels, I like to take an apple sauce pouch, or even baby food pouch with me. It’s way healthier than processed gels and typically only contains blended fruit. I usually like to wait until after km 14 to fuel up, so that I can get that second wind and finish the race strong!

If you’re running a race soon, good luck to you! If you try any of these tips out, I’d love to hear your experience with it - please share :)