Carbohydrates are a kind of nutrient your muscles use for energy. Carbohydrates contain four calories per gram and are in plants, sugars and starchy foods such as bread, rice and potatoes. Your body can store enough carbohydrates as glycogen in your muscles and liver to fuel one to two hours of bike riding. Once your glycogen stores are full, your body stores extra calories as fat--another form of stored energy.
Function
Your cells break down carbs and fat to fuel muscle contractions. During leisurely bike rides, carbs provide only a small percentage of the energy you use. However, as the intensity of your riding increases, fat breakdown can’t keep up with your energy demands, and a larger percentage of your energy comes from carbs.
Types
A useful way to classify carbs is by glycemic index, or GI. Low GI foods release sugars slowly into your bloodstream, providing a constant source of energy at a rate so that your muscles can use them. Low GI foods include whole grains and some plants such as celery. High GI foods dump all their sugars into your bloodstream at once, making it hard for your body to use them all before they are stored as fat. High GI foods are useful when you are “hitting the wall,” and your body is severely glycogen-depleted. High GI foods are simple sugars such as high fructose corn syrup, processed grains and some plants such as watermelon. Fiber is a carb your body doesn’t digest.
Time Frame
If you are a cyclist on a low-carb diet, the timing of your carb intake is essential. Eat carb-rich meals before your workouts to provide the fuel you need for your ride. If you are riding for more than an hour, eat some carbs to keep your muscles going. Eat carbs immediately after your workout to replenish muscle glycogen and recover. Taper your carb consumption throughout the day as your muscles’ carb absorption slowly decreases after your workout.
Some cyclists try to increase their fat metabolism by fasting before their rides. Dietitian Ellen Coleman cautions against fasting because it detracts from the quality of your workouts.
Weight Loss
Weight loss is a question of balancing the calories you eat and drink against the calories you burn. According to the Mayo Clinic, low-carb diets work because they lower your overall energy intake, not because of the nature of carbs. Because cyclists need carbs to fuel their training, you will feel sluggish and ride poorly if your carb consumption is too low. Instead of cutting out carbs completely, replace processed carbs such as white sugar, flour and rice with healthy carbs from whole grains, fruits and vegetables.
Effects
Cycling is a sport in which your weight counts. Your power-to-weight ratio determines how fast you ride. If you lose weight while maintaining your strength, you will ride faster, especially uphill. It is much less expensive to lose weight off your body than to buy a lighter bike, and it is much easier to lose weight than it is to gain strength.
References
- Trifuel.com: Fast to Burn Fat?
- Mayo Clinic: Low-Carb Diet
- "ACSM's Resources for the Personal Trainer"; American College of Sports Medicine; 2006
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