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.
More: Perfectly Natural Fuel
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.