Adventure September 2, 2022

Beware the “Bonk”

Fueling your body for optimum performance

The heady days of summer in Sun Valley can beguile us with ample Aspen-filled hikes to crispy cool summits and ribbons of sweet singletrack unfolding into the distance. With limitless options to recreate, intrepid explorers can find themselves on a different adventure every day. Paramount to your success on these wanderings is properly fueling your body, not just for peak performance during the event, but also for proper recovery.

Properly fueling up the day of, and even a couple of days before, a strenuous activity can impact whether you have an enjoyable time or whether you hit a brick wall on the trail. If you fail to plan accordingly, and you run out of water or food when your body needs it most, it might result in the dreaded “bonk,” which physiologically is a total glycogen depletion from the muscles and liver. Physically, it feels like someone cut your power cord.

“Bonking is no bueno,” says Alan Jacoby, a local bikepacking endurance athlete who mountain bikes an average of 30 miles a day. When you’re planning a long day of activity, “you’ve gotta shovel coal in the furnace and force yourself to sip water constantly,” says Jacoby. This is especially true if you’re planning a more epic adventure, like a multi-day hiking or biking trip, especially at extreme altitudes. Take it from Mark Pattison, who summited Mt Everest in May 2021. “I have run out of water on Mt Whitney, Mt Everest and other smaller peaks, which resulted in me bonking,” says Pattison. “No energy equals potential frost bite, altitude sickness, and usually not achieving your goal.”

Here, we’ve outlined what you should eat and when to ensure you’re firing on all cylinders the next time you hit the trails.


It’s best to consume some complex carbohydrates two to four hours before action for sustained energy, so don’t just roll out of bed and pull on your sneakers. A good carb-based breakfast will raise your blood glucose and increase liver glycogen, which your body will use during activity. This will spare muscle glycogen and prolong the onset of fatigue.

Select easily digestible, light carbohydrates so you don’t feel sluggish. Some good choices are eggs, whole grain non-sugary cereal or oatmeal, whole-wheat toast, or low-fat yogurt. Or you could make yourself a healthy smoothie; a good homemade smoothie should include a protein source (powder, milk, yogurt, kefir), fruit, vegetable, and healthy fat source (nuts, seeds, avocado). It’s okay to add some optional extras, but make sure they include minimal added sweetness from honey/agave/maple syrup or other flavor enhancers like vanilla, cinnamon, ginger, or turmeric. Pattison favors his “Seven Summit Smoothie” before a long hike, which includes protein powder, strawberries, blueberries, almond butter, Chia Seeds, Almond milk, and collagen. “This smoothie can really sustain me,” he says.


Strenuous activity can suppress your appetite, so plan to feed yourself anyway as calories play an important role in regulating body temperature.

Eating during activity that is longer than 90 minutes is also a good idea, especially if it is particularly intense. This allows carbohydrates to enter the bloodstream and the muscle, maintaining your blood sugar and giving muscles a continuous source of energy.

If you fail to eat after about two hours of intense activity, your performance will start to gradually decline until the dreaded bonk occurs. When blood sugar drops, your body will burn through its remaining muscle glycogen rapidly. Then, a few nasty things will happen:

• Muscular performance will decline. Your power/pace will rapidly decrease.
• Lowered blood sugar will impair decision making and technique (a particularly big issue during competition).
• Muscle breakdown increases.
• Rate of perceived exertion will dramatically increase.

In short, the longer and harder the session is, the more carbohydrates you need. Consuming plenty of calories during training will also help you to meet caloric requirements for the day and enhance recovery for the next bout of exercise.

“My appetite is constantly changing [during activity],” says Jacoby, “but snack variety for all-day epics usually include peanut M&M’s, pumpkin seeds, chocolate/coconut Luna Bars, dried fruit, beef jerky, or GU Chews. I have a habit of overpacking food, so I thankfully have never run out.”

Nutrient dense day hike snack ideas include trail mix, nuts and seeds, peanut butter, crackers, cheese, beef jerky, energy bars, granola bars, fresh or dried fruit, or a sandwich.

If you like to eat fruit on hikes, consider picking durable fruits like an apple, instead of a banana that may end up squished in your pack. And for dried fruit, be aware that your stomach re-hydrates the fruit to digest it, so if you don’t replenish your body with enough fluids, dried fruit could end up dehydrating you and making you feel light-headed, which undoes the effort altogether.

When selecting dried fruit and granola bars, look for options that don’t have any added sugars, as high sugar levels can work against you, sparking a short burst followed by an epic energy crash.


For strenuous activity, carbohydrates should be consumed within 30 minutes of finishing to replace the glycogen stores in your muscles and help your body recover faster. This can be done with a sports drink (see sidebar) or a carbohydrate-rich snack such as a fruit smoothie. Exercise also naturally lowers blood sugar, and if it lowers too quickly or too low, you could become hypoglycemic. That’s why carbs are important to refuel and recover from a tough workout. You need some carbs to prevent muscle breakdown. So, how do these carbs differ?

Simple carbs: These carbs have one or two sugars in them. Think sweets: candy, sugar, cakes, and cookies. These should be avoided when you’re trying to get fit, except for special occasions or an indulgent treat.

Complex carbs: As their name suggests, these carbs have three or more sugars in them, and they’re important post-workout. Your body needs complex carbs to rebuild glycogen stores that are important for recovery. Complex carbs also take longer to digest and aid in digestion because they often contain fiber. Some complex carb options include brown rice, whole-grain pasta, whole-wheat bread or cereal, sweet potatoes, fruit, milk, and yogurt.

The rest of the day, your body still needs carbs to replenish, but you do not want to cause a spike in blood sugar. Focus on fiber-rich, complex carbs like fruits, vegetables, sweet potatoes, brown rice, and quinoa. This is also a good time to consume some lean protein and healthy fats.


You need plenty of water before, during, and after activity. Research says you perform your best when you consume between 400 to 600 ml of water pre-workout. Not only that, your perceived effort remains lowest when the water you consume closely matches how much you’ve lost through sweating. In other words, the more you drink, the easier your workout feels.

Drinking water does so much more than put liquids back into your body after you sweat. It also replenishes electrolytes, sodium, and glucose when you exercise. But what’s more, water helps regulate your body temperature so you can cool down after that workout. It also helps ward off muscle cramps, removes toxins from your body, and transports nutrients to parts of your body that need it most after expending so much energy.

Pattison says, “I always carry a water bottle or two filled with nutritional electrolytes like NUUN tablets or Q Sciences.” Jacoby also suggests bringing treatment tablets as a back up, in case you’re forced to find a water source nearby.

“You need to do everything you can to sustain your body with the right nutrition and fluids to along the path,” says Pattison, “especially at altitude where your appetite gets suppressed but you burn more calories. You’ll never be a champion if don’t prepare and eat/drink like a champion.”

Do Sports Drinks, Energy Bites and Protein Powders Live Up to the Hype?

For some athletes, eating solid food in the middle of a workout can cause digestive upset. In these cases, easily consumed sports gels, chews, or drinks may help. Food and fluid intake around workouts should be determined on an individual basis with consideration for an athlete’s gastrointestinal tract tolerance, as well as duration and intensity of the workout. It is important to replace lost fluids as well as provide carbohydrates to maintain blood glucose levels while working out for longer than one hour.

GU Energy Chews pack energy-dense calories to meet the demands of all types of activity and contain carbohydrates (maltodextrin and fructose) that use non-competing pathways that can help maximize absorption, increase carbohydrate utilization, and diminish stomach distress, for energy that kicks in quickly and stays with you.

Liquid IV Hydration Multiplier is a non-GMO electrolyte drink mix powered by Cellular Transport Technology (CTT) to deliver hydration to the bloodstream quickly and more efficiently than water alone. Each electrolyte powder drink mix contains five essential vitamins including Vitamins B3, B5, B6, B12, and Vitamin C. It’s also gluten-free, soy-free, and dairy-free.

Salt Lake City-based Nanohydr8 is a versatile health, hydration, and energy-boosting drink full of amino acids, electrolytes, vitamins, and minerals delivered using the brand’s proprietary Nano technology, which reduces nutrient participles 1000 times smaller than competitors for the fastest absorption on the market. Each drink can be used to energize before exertion and recover nutrients and electrolytes post-workout.

Nuun is a sports drink tablet, enhanced with electrolytes and filled with a natural, low-calorie fruity flavor. Mix with water for a hydrating beverage to keep you powering through your next workout. Nuun’s tablets use no artificial flavoring or sweeteners (sweetened with high-quality Stevia only) and are keto-friendly.

Breathe fire into your physical performance and sharpen your mind with Q Sport from Q Sciences, a well-balanced fusion of natural caffeine, chia seed oil, amino acids, and supportive nutrients. Q Sport boosts physical and mental energy, increases nitric oxide for enhanced blood flow, reduces muscle soreness after a workout, and improves mood and enhances cognitive function.

Vital Protein’s protein powder boasts hyaluronic acid and vitamin C, powerhouse ingredients that provide glowing wellness benefits. In addition, it contains 20g collagen to support healthy hair, skin, nails, bones, and joints. Flavorless and odorless, also gluten- and dairy-free, Vital Proteins is easily digested and dissolves in cold or hot liquids, like coffee, tea, and smoothies.

This article appears in the Summer 2022 Issue of Sun Valley Magazine.