Carbs and Candy… While running

Eat snacks and run!

I am not a runner. I love to be active, and I work out in the gym and spend a hefty chunk of my free time hiking up mountains (either on my feet or on skis). But running is not my forte– it’s just never been my thing.

Until now.

You see, about a month ago I signed up for my first half marathon on a whim, looking forward to a new challenge. As a someone with practically no running experience and about a month to train, the idea of researching how to improve my running form, looking up training schedules, or following any kind of pre-made half marathon regimen stressed me out. So, I decided to just wing the whole running part of the prep (turns our that wasn’t not the smartest idea.. but I’ll get to that).

While I may not be a great runner, I am an expert snacker. So, I found the idea of  researching optimal training and race-day snacks pretty motivating. I kid you not, this is how my brain works.

I knew the drill at these big organized races: there are multiple stations along the way where they hand out water, sports drinks and all sorts of nibbles to keep the athletes hydrated and energized.. I figured that at a swishy corporate-sponsored race with over 10,000 runners, the snack selection would be top-notch.

But I didn’t want to risk my success on just snacking willy-nilly on whatever treat caught my attention, so I did my due diligence to understand the optimal recipe for food consumption during prolonged exercise.

Here’s what I learned:

How we get energy

Humans get their energy from three different sources: fats, proteins, and carbohydrates. Each is essential for different tasks. Depending on what our body is doing, it uses one type of energy more than another.

For running – or any other aerobic exercise, like biking, or swimming– its carbohydrates that our bodies use for energy. Interestingly, while there are loads of different sources of carbohydrates, once they get into our blood stream, our body turns them all into the same carbohydrate: glucose.

When we exercise, our cells use glucose and turn it into tons of tiny little rocket packs called ATP that our muscles can then use to power themselves. On the simplest level, when it comes to exercise, the more glucose available for our bloodstream, the more energy we have available to us.

Our muscles store a certain amount of glucose, and our livers have a backup supply. However, when we use move our bodies fast enough or hard enough for a long period of time, we deplete our glucose stores. While our body can make more glucose from other energy storage (usually by turning fat cells into glucose) it can take a long time. In the meantime, unless you find a way to give your body more ready-made glucose, you can experience muscle fatigue and a decrease of performance during exercise.

Race day!

Refuelling backwards?

Enter snacking! Once we’ve used up our glucose storage, the easiest way to get more energy to our cells is to eat more carbohydrates. After we exercise for more than one hour, we need to consume about 30-60 grams of carbohydrates per hour to provide enough energy for our cells to keep going at their optimal performance.

But here’s the catch: not all carbohydrates are made equal! The amount of time it takes the carbs to get into our bloodstream and start energizing us depends on the type of carbohydrate we eat. And, the carbohydrates that benefit us most during a prolonged workout are actually the opposite of what you associate with “healthy” carbs.

Let’s get granular with this: glucose is a one-unit sugar, or carbohydrate molecule called a monosaccharide (mono means one and saccharide means sugar molecule in fancy jargon). We use monosaccharides as our currency for energy in the body. Once one of these simple molecules gets past our intestine, it can take the blood highway straight to our muscles cells to be used up. These guys are like the delivery trucks that can bring energy to all of the different shops (or cells) in our body.

Healthy whole grains like wheat flour or oats are considered complex carbohydrates because they are made up of a bajillion monosaccharides all chemically stuck together. They are like those huge cargo ships at the port: they take longer to digest because we first need to break them down into their single-unit glucose pieces, or unload the freights off of the docks. Most of the time, this type of carbohydrate is better for us, because it means we don’t get an overload of glucose in our blood all at once, and whole grains also carry a bunch of useful nutrients and vitamins that we need to stay healthy.

The carbohydrates that benefit us most during a prolonged workout are actually the opposite of what you associate with “healthy” carbs.

When we are doing exercise, though, we want to get energy into our bloodstream as quickly as possible, and we don’t want to use that precious time (or energy) breaking down chunky whole-wheat molecules into smaller ones.

So, during a long run, it’s good to stay away from those otherwise healthier complex carbs and stick to monosaccharides to replenish your energy source. There are actually lots of different monosaccharides, aside from glucose. Another one you’ve probably heard of is fructose.

Fructose is similar to glucose, but it takes a little longer to become an available energy source. Once fructose makes it past the intestine, it takes a detour into the liver to get a full body transformation into a glucose molecule before it can be used as energy by our cells. It’s like a container that is the incorrect shape to fit on the back of a semi, and must be altered to be compatible with our roads.

Quick! Get the energy to your cells!

Now, when it comes to exercise snacks, we want to get the quickest type of energy—glucose—to our cells. So it would make sense that eating straight glucose during prolonged exercise would be the best way to get that energy store up, right? To my surprise, this isn’t true!

The best way to get the most new energy to our cells as quickly as possible is to eat a mixture of fructose and glucose. In order to get sugar molecules from our intestines into the bloodstream, they have to pass through very specific tunnels. We only have a limited amount of glucose tunnels, so if we eat too much glucose too fast, the sugar molecules get backed up in the intestines, slowing down how quickly our cells get more energy. Because fructose is a different shaped container, so to speak, it’s got it’s own tunnel into the blood via the liver and separate from glucose. So, by eating a mixture of the two, you can speed up how much sugar gets to your blood by using more intestine tunnels.

The Verdict


The best energy source during a workout is a fructose:glucose mix. Not only do long distance athletes absorb energy quicker this way, but they experience less bloating or uncomfortable stomach issues during exercise, because the food they eat hangs out in their intestine for less time!

Most commercial energy drinks, gels and chews are already prepared with both fructose and glucose in them, so if you are an athlete who uses pre-made sports gels, you’re probably already reaping the benefit of this mix.

But do you know what else is made up of a perfect fructose:glucose mixture? Table sugar! And guess what?! That means that any old grocery-store candy is going to give you the optimal nutrients to maintain your endurance exercise performance. Who knew that eating jellybeans and jujubes could ever be the healthy option!

Did it work???

Firstly, I was incredibly humbled by this run. 21 km is really far when you have to go the whole distance on your own feet! I now understand why people train for this kind of thing, and I think I really could have benefitted from doing a little research on the running aspect of this event. But I am proud of myself for completing the run and I even managed to beat my goal time!

As for my snacking? Well.. there was definitely room for improvement. On the carb front, I ate 15 g of carbohydrates from an energy goo every 40 minutes. I felt pretty energized for the first 16 km of the race and felt that my snack system was working! I also drank electrolytes at every water station. I was feeling fresh and energized and relatively good until the last 3 km.  I finished the race feeling very dizzy and lightheaded– I was sent to the medic tent at the finish line only to be told that I was dehydrated, likely from consuming tooo many electrolytes! What I didn’t realize was the energy goo also had electrolytes packed into it…

Lesson learned: I should have stuck to the gummy bears I packed for myself. And maybe next time, I’ll do a little more research beyond the snack aspect (snackspect) of running a half marathon.

Eating my gummy bears… after the race.



**The evidence to support my claims has come from a review article written by Asher Jeukendrup***








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