For the last 40 years, carbohydrates have been accused of a laundry list of crimes against humanity, including multiple counts of conspiracy to make us fat. This is partly because too many of us fill our bellies with the wrong kinds—breads, chips, crackers, and pastas made from refined flour that's been processed to within an inch of its nutritional life. Cyclists in particular have also gotten confusing messages about carbs thanks to trends like the protein-centric, grain-shunning Paleo diet (Search: What is the Paleo diet?), and from pro riders who have gone public about going gluten-free. All this has many of us pedaling scared from an essential fuel source that makes us faster, fitter, and smarter on the bike. But harnessing the power of the carbohydrate is not as simple as stocking a pantry full of bagels and filling your bottles with sports drinks. To understand why, you first need to consider five irrefutable facts.
Fact: Carbs make you a speedier, savvier rider—and may even help you get leaner.
Carbs are so powerful, just a hint of them makes you go faster. British researchers discovered that endurance cyclists who swished and spit a carbohydrate beverage without swallowing a drop were able to shave off a full minute in a time trial, while those who swished a similar noncarb beverage saw no performance gains.
How's that possible? When the researchers did MRI scans of the riders' sweaty noggins, they found that when carbohydrates passed over receptors in the mouth—even without sugary sweetness (the solution was flavorless)—reward centers lit up in the brain, which in turn provided the impetus to push harder. In other words, the brain was tricked into believing that fuel was on the way, so it gave the okay to the legs to keep cranking away without conserving energy. All this from a swish.
So what happens when you ingest the stuff? Your body uses it to make glucose, or blood sugar, the fuel that drives athletic performance. Within limits, "the more carbohydrates you consume during endurance exercise, the better you perform," says sports-nutrition researcher Asker Jeukendrup, PhD, global senior director of the Gatorade Sports Science Institute. In a study of endurance cyclists completing a 238-mile race, those who took in the most carbs (the mean was 52 grams an hour for the 16-hour event) posted the fastest times.
And the benefits go well beyond performance. "All systems and tissues in your body use carbohydrates in some capacity," says Stacy T. Sims, PhD, a Stanford research exercise physiologist and nutrition scientist who has consulted for pro cycling teams. Carbs fuel your immune system, enhance fluid absorption so you stay hydrated, and are even critical for muscle recovery. In fact, if you fail to feed your body the carbs it needs, it will generate them by breaking down muscle tissue. You also need carbs just to think: The brain gobbles glucose exclusively, says Michigan-based sports dietitian Donna Marlor, BSN, RD, CSSD. It needs a lot, even when you ride, because it's busy picking good lines and strategizing your next move in the pack. And maybe most surprising, carbs prime the furnace for fat burning—the process of digesting them stimulates the hormones your body needs to fully break down and use fat.
Fact: Not all carbs are created equal, but there's a time and place for most of them.
Carbohydrates fall into two categories, simple and complex. Simple carbs are made from one or two sugars, like fructose or glucose. They're found in such sweeteners as cane sugar, corn syrup, maple syrup, brown sugar, and honey. Because your body digests them quickly, they trigger a quick surge in insulin, the hormone that ushers glucose from your bloodstream into your cells to fuel activity. Refined and processed foods like white bread, white pasta, cakes, and pastries also fall into this category because they're stripped of fiber and other compounds that slow digestion and the insulin response. Simple carbs get a bad rap because sudden spikes and falls in blood sugar have been linked to overeating and, subsequently, to increased fat storage.