What is the best sports nutrition product? What kind of food should I take when I’m hiking? What will give me the energy I need for my long running or cycling events?

These are all common questions that endurance enthusiasts (professional, amateurs and weekend warriors alike) either type into their favourite search engine or pose to their community of like-minded athletes.

What’s the answer?

Well, annoyingly, it can vary depending on the person, event and environmental conditions.

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Your friendly sports nutritionist would give you the same answer—it depends.

This article will review some of the common fuelling options that are on the market today and simplify how they are intended to work. Hopefully, you will then be able to choose an effective fuelling strategy that you enjoy!


Slow vs. Fast

Depending on where you are in your event, be it a 10-kilometre run, long-distance Gran Fondo or overnight hike, you want to have a variety of fuelling options that satisfy both a long-term energy release and short, quick bursts of energy. But what does that mean?

Quick-release energy, or “fast fuel,” refers to products that are designed to be absorbed into your bloodstream and effective in under 30 minutes. These products are often high in simple sugars (usually glucose), are easily digestible, and tend to give you a burst of energy you can actually feel. Think syrups, chews or carbohydrate drinks.

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Comparatively, slow-release energy is more like having a steady stream of energy entering your bloodstream over time. You may notice that you don’t have that speedy burst; more than two hours can go by and you’re still killing it out on the trails.

The physical mechanism here is more complex. It could be harder to break down macronutrients, such as fiber, protein or complex carbohydrates, or it could be a mix of simple and complex macronutrients working together to slow down the absorption of glucose. Examples are sandwiches, protein bars and high-quality chocolate.


Quickly absorbed “fast fuels”

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If you’re looking for that noticeable, super speedy boost of energy, fast fuels are good products to reach for. They are usually glucose heavy, easily absorbed and may contain other enhancers such as electrolytes or modified carbohydrates that are in an easily absorbed format. Glucose is the main fuel your muscles require for actually creating energy. By consuming glucose and similar simple sugars, such as dextrose and fructose, you are directly consuming the most efficiently processed fuelling substrate.

Sounds great, right? But what happens when you light gas on fire? It burns, quickly! You remember how you feel after the effects of a sugar-high have worn off…

Pros of “fast fuels”:

  • you tend to feel a burst of speed or energy
  • if you are too low in blood sugars (hypoglycemic or bonked), they are effective ways of getting you the sugars you need for basic body functions
  • you are using less energy to digest these products, meaning more energy for your effort.
  • easy to consume as they are usually syrups, liquids or dissolve quickly.


  • highly concentrated forms of sugars and fibers can upset your tummy if you aren’t drinking enough water
  • you need to consume these products more frequently to keep your energy levels up
  • energy is not long-lasting (you will also feel the crash)
  • due to the concentration of solutes, they often cause palate distress (roughness or sores in your mouth from ongoing consumption)

Examples of products:

  • Traditional carb gels: Gu Energy, SIS. Tailwind
  • Chews: Honey Stinger, Clif Shot Bloks
  • Fruits: Oranges, grapes, berries, ripe bananas

Active Ingredients:

Glucose, Dextrose, Maltodextrin, Fructose

When to consume “fast-fuels”: Start 30 minutes into your effort and continue every 20 to 30 minutes throughout the duration of the event.


Slow-release fuelling products

For endurance activities (longer than three hours), one of the keys to success is managing your effort expenditure: preventing yourself from overworking too soon in the process. Often this is managed through a moderate and steady pace, where you aim to keep your heart rate in zone two or less. To complement this long-haul grind of an activity, it’s a good idea to have a steady stream of energy in your system and to maintain your hydration. Slow-release fuelling products are a great addition to these endurance-type activities.

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Ultimately, your body will still use glucose for energy; however, instead of only supplying glucose and simple sugars, you will transform all other foods and macronutrients into glucose. Fats, proteins and complex carbohydrates are all digested, broken down and rearranged into glucose in your own body. It just takes a little while longer for your body to do so, rather than getting a direct hit. Alternatively, when there are simple sugars in the food already (such as honey, jam or sugar), and they are mixed with complex macronutrients such as the fibre in the bread of your PB&J or the cocoa butter in your chocolate bar, unlocking the easily absorbed nutrients in the food takes a bit of time.

Once you have this process going in your body, and sustained, you’ll notice that your energy levels tend to remain intact as your progress in time during your endurance activity. Your body is continuing to break down macronutrients into the short-little glucose and simple sugar units that make your muscles fire. You are receiving a steady stream of energy that keeps you going at your moderate pace for a longer duration. Ensuring this steady stream of energy with little-yet-often hydration also means that your stomach won’t become oversaturated, thus preventing GI distress.

Pros of slow-release fuels:

  • You maintain your blood glucose supply and energy, steadily over time
  • A complex mixture of macronutrients is not super-saturating your digestive system, protecting it from upset
  • Usually higher in fat and/or protein contributing to more calories per serving than with carbohydrate gels


  • If you are too low in blood sugars (hypoglycemic or bonked), you will need simple sugars to regain autonomic body functions before you need complex foods
  • Often more difficult to consume as they require more chewing and digesting

Examples of products:

  • Chocolate: 7 Summits Snacks
  • Nut Butters: Muir, Trail Butter
  • Date or Protein Bars: RX Bar, Quest Bar
  • Waffles: Naak or Honey Stinger
  • Foods: Sandwiches, pizza, hamburgers

Active Ingredients:

Combinations of macronutrients you know and understand

When to consume slow-release fuels: Before you start, and/or as you continue your effort on an hourly basis.

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Now armed with a better understanding of effort-focused fuelling, we encourage you to try out these different strategies on your next adventures!


This article was sponsored by Seven Summits Snacks

Kristyn Carriere has a BSc Nutrition and Food Science. She is an everyday marathoner and the founder of 7 Summits Snacks.

Founded in 2019 in memory to RH Fisher’s last adventure, Seven Summits Snacks has a passion for chocolate and health. We provide purposeful nutrition and satisfying chocolate products to get you through your next adventure. From indulgence to sport performance, we have chocolate snacks to fit your needs at different times of the day.