What function do carbohydrates serve in the body?
Carbohydrates are the most important source of energy for the body. It must be present to metabolize fats at the rapid rates needed to support the caloric demands of exercise and sports competition. As the intensity increases in an activity, the greater the reliance of the body on CHOs. In addition, it is the only macro nutrient that can provide energy for anaerobic activities such as sprinting. Adequate CHO intake also helps spare muscle tissue, without it, the body will turn to the breakdown of muscle protein to make up for the deficit in needed CHO. Lastly, it is the primary energy sources for the nervous system. Our nerve cells do not store CHO like muscle cells do, rather, its source is the bloodstream. Without adequate levels of CHO in the bloodstream, nerve cell function suffers, and can have adverse effects on the body and dramatic effects on exercise and sport performance.
The body prefers to use CHO as fuel during exercise and is broken down into the body via aerobic or anaerobic means. At low to moderate exercise levels, or when exercise intensities increase to 40-60% of VO2 max, CHO are primarily aerobically metabolized for energy and is the major source of energy. Activities such as sprints or high intensity bouts of exercise only use CHO because it is the only substrate that can be metabolized fast enough to support this level of anaerobic exercise. Because most sports require a burst of intense activities, athletes who restrict carbs in their diets negatively affect performance.
What are different types of Carbohydrates?
Fiber, a complex CHO cannot be digested and absorbed by the body and does not contribute to the body. The indigestible fiber (normally eaten from plant foods), provides little to no energy. However, active individuals who eat adequate fiber and fluids will have a healthier gastrointestinal tract that moves food and fluids efficiently and improves better absorption of nutrients into their bodies.
The richest sources of carbohydrates are fruits, grains, and vegetables. Dairy/alternatives and legumes, nuts/seeds and soy products from the protein food groups also provide quality sources of Carbohydrates.
How are carbohydrates utilized?
The body stores limited amounts of carbohydrates (400-600gms) which is why it is important for us to replenish carbohydrates. Failure to replace stores in our diet, can lead to low energy levels and decreased motivation. Diets consisting of 60% to 70% of total calories from CHOs have been shown to increase resting muscle glycogen levels, which can result in delayed muscle fatigue. This is the reason why many endurance athletes will “carbo load” prior to an event. Replenishing glycogen stores used during exercise can take 20 hours or more. If you are a recreational athlete that trains aerobically 3 to 4 times a week, you must play close attention to proper CHO dietary intake in order to supply the demand on your body.
How much carbohydrates should I eat?
Depending on your age, sex, activity level, and overall health, your carbohydrate requirements will vary. According to the Mayo Clinic (1), 45 to 65 percent of your daily calories should come from carbohydrates. That’s equal to about 225 to 325 grams of carbs if you eat 2,000 calories a day
Eliminating CHO from your diets can have adverse affects on your overall health. Staying within an acceptable amount of CHO (such as the Zone Diet 40%CHO/30% Pro/ 30% fat) and choosing whole grains and fruits combined with leans proteins and fats will keep you healthy. Athletes will perform better choosing a diet that has at least 50% of the calories from CHO. If you have specific questions or medical issues concerning your health, seeing a registered dietitian or nutritionist maybe a good idea.
Arlene Alpuerto, MS Ex Science
Coming Soon Part 2: Protein