Should You Eat Or Drink Your Calories? By Nate Helming

Bonk or cramp? There’s a thin line between the two and that’s the line triathletes walk in long-distance training and racing. If you don’t take in the right amount of food and fluid, you’ll bonk. Take in the wrong stuff, or at the wrong rate, and you face a wide array of GI issues, cramping among the least of them.

So how do you get the calories and fluid you need without taxing your GI system? This article compares the two primary fueling methods triathletes use while training and racing—chewing calories versus drinking them.

There is general consensus among coaches, exercise physiologists and nutritionists that for training sessions and races beyond two hours, athletes should supplement with something in order to maintain their performance output. When an athlete’s glycogen stores drop too low, they experience significant fatigue and a sharp decrease in performance. In its most extreme form, athletes hit the wall or bonk.


That’s where energy drinks and bars come in—to provide a ready-made energy supply that helps athletes continue to train and race at their best.

But, eat too much or at the wrong times and you can experience all types of complications in the form of gastrointestinal (GI) problems, stomach aches and nausea, which can slow you down. Alternatively, if you don’t consume enough fuel, you can experience early fatigue and a decrease in performance. Finding the right balance is imperative.


In addition to fueling, athletes need to hydrate to perform well. Let’s highlight two of the ways dehydration negatively affects the body.

First, as blood plasma depletes due to dehydration, the heart’s stroke volume—the volume of blood pumped per heartbeat—diminishes. Due to this reduced cardiac output the heart has to pump faster just to deliver the same number of oxygenated blood cells to working muscles. This phenomenon is known as cardiac drift and reflects the additional stress heat places on the body. If you’ve ever experienced an elevated heart rate that stays way above your effort level, you’ve probably experienced this phenomenon.

Second, dehydration compromises the body’s thermoregulatory response and its ability to stay in homeostasis. As part of the body’s cooling mechanism, it pulls heat away from the body through sweat evaporation. The body also cools through the principals of convection (dispersal of heat through blood circulation) and conduction (body heat radiating away). The blood vessels expand to allow additional blood to circulate into the superficial capillaries in the skin to pull heat away from the body.

Without taking in additional fluids, your body can only perform for so long without purposely slowing down to protect the vital organs from overheating. You can usually tolerate up to a 2 to 3 percent loss in body water and still perform, but beyond that you may start to develop minor symptoms such as headaches, dizziness, nausea, disorientation and sluggishness.

Ultimately, athletes need to manage the twin perils of glycogen depletion and dehydration in order to perform at peak levels in events lasting longer than 2 to 3 hours, and especially in hot and humid conditions. For hot Ironman events such as Kona, it’s imperative to nail down a solid nutrition and hydration strategy.

Let’s compare two different fueling strategies to see what’s best for you.

Drinking: The High-Calorie Bottle

This fueling method tackles both fueling and hydration needs at the same time. These super-calorie bottles contain mostly carbohydrate (some with additional fat and protein) and are specifically targeted for the 2- to 3-plus hour events with greater fueling requirements.

The Pros: Chewing solid food can slow the digestive system down. Drinking calories is an alternative way to get them in, especially for athletes who deal with stomach cramps. Athletes can conveniently fuel and hydrate at the same time with these sports drinks and powders. This makes it easy to grab and go when constantly on the move. If done correctly, athletes can meet their fueling requirements while also tackling some of their hydration requirements.

The Cons: Some people believe that these high-calorie bottles are responsible for the majority of GI issues experienced by racers, and they offer compelling evidence in support. As it turns out, the rate at which we should hydrate is different from of the rate of fueling, making it unrealistic for one product to optimally address both.

High-calorie bottles actually slow fluid absorption through the gut, hampering hydration efforts. When the body encounters a fluid that is thicker than blood, it has to pull fluid from the body into the small intestine to dilute it to an acceptable level. This process can only help so much before it contributes to both dehydration and backing up the GI system.

It’s way too easy to slurp down large amounts of calories in liquid form that far surpass the gut’s ability to handle them. Think of the gut as a tollbooth and the fuel, in this case carbohydrates (CHO), as the cars passing through. On any given day, cars (CHO) must stop to go through the tollbooth (gut). During regular traffic hours, the gut can more than handle the amount of carbohydrates coming its way with minimal backup.

Now picture this tollbooth during rush hour traffic. The rate at which carbohydrates show up far surpasses the rate at which the gut can process them, contributing to a nasty build up in traffic. Since the gut cannot double its rate of absorption, athletes experience stomach cramps, bloating and nausea when ingesting too much carbohydrate too quickly. So while super-calorie bottles work to get fuel in, they can be too effective, creating serious backup and GI issues that slow athletes down in a different way.

Regardless of this innovative solution, athletes still risk failing to meet their hydration requirements as the processing of carbohydrates slows down the ability to take in fluids. Simply put, with the high-calorie bottle athletes are either well fueled but under hydrated or properly hydrated but over fueled.

Chewing: The Separation of Nutrition and Hydration

While the super-calorie bottle does have its merits, some coaches and athletes would rather simplify their approach to fueling and hydration to minimize potential GI issues. People in this camp believe you should chew your food and focus on hydration in your bottles.

The Pros: When athletes chew solid foods, the entire digestion process slows down the rate at which fuel goes from the stomach to the small intestine and from the small intestine into the bloodstream. Digestion in the stomach is the key regulator here. Chewing your food slows down the rush of calories to the gut. This gives the body time to process what you’re putting into it, significantly reducing the possibility of GI issues.

Also, without significant calories in the bottle, athletes can focus on optimal hydration. While temperature does not significantly affect fueling demands for an event, it most certainly affects hydration demands. By keeping nutrition and hydration separate, you can more effectively address both needs.

The Cons: The biggest downside of this approach is the need to carry solid foods while training and racing. It’s impractical to carry enough food for an entire Ironman so athletes often have to refuel with what’s available on the course. Sports gels, drinks and powders are popular for a reason: they are convenient and they can be found on most racecourses. While they may not be perfect, some fueling is better than no fueling and these products are easy. Coaches recommend their athletes actually train with these on-course products so they can get used to them before the event.

Another downside is potential stomach cramps that creep up while chewing food on the run. While it’s relatively easy to fuel on solids on the bike, it’s difficult to ingest the same amount while running without feeling any repercussions. As most of you can attest, trying to run too soon after a big meal and you’ll experience cramps and even nausea. The energy requirements of running combined with the constant jostling stress the stomach and its digestion too much. A high-calorie bottle provides the energy needed while minimizing stomach cramping and digestion.

What’s Better?

Significant variability exists between athletes. Some do quite well on snickers bars and coke (one of my personal favorites), while other guts are quite sensitive to even the slightest changes.

A high-calorie, high-concentrated bottle is convenient, making it easy to deliver the much-needed calories while racing and training. It’s also relieves the digestive system when chewing becomes difficult. Plus, gels, drinks and powders dominate most aid stations at long triathlon events, making it a virtual prerequisite for athletes to fuel on them just so they can get used to what’s being offered on race day.

Unfortunately, it’s all too easy to surpass the gut’s absorption ability with this strategy. This can cause serious backup, resulting in tough GI issues and even dehydration. This can have more serious consequences in hot and humid environments when the hydration demands are especially high.

On the other hand, athletes can more optimally address both their hydration and fueling demands by keeping them separate. While some sloshing may occur, this digestive process helps ensure that you don’t flood the small intestine with more calories than it can handle. By drinking lower concentration fluids, the body can more easily absorb the fluids with minimal backup and less dehydration.

Regardless of the strategy you employ, it’s important to be aware of the pitfalls of both. If you fuel and hydrate with high-calorie bottles, be careful not to take in too much at any one time. If you fuel and hydrate separately, be sure to pick foods that you can chew and digest easily.

Practice, refine, and revisit your approach constantly. Nutrition should be part of your training regimen. If you do experience GI issues while racing, it’s safe to say your approach could use some tweaking. You’ll also want to modify your strategy depending on the duration and type of event or training session.

Your approach will continue to evolve and change as you mature as an athlete, especially as you start pushing harder for longer periods of time.

And while every athlete is different, it’s still worth finding out what works for others and experimenting with those methods yourself. Just don’t tweak anything too close to your next race.