Key Points

1. Our body needs a steady supply of energy (calories) to support day-to-day activities. Daily consumption of dietary carbohydrates helps the body maintain a consistent level of blood glucose (blood sugar).

2. It is important to match dietary carbohydrate intake to activity level as consuming excess energy can contribute to weight gain, whereas not enough carbohydrates can hinder exercise performance.

The Bottom Line Up Front

Although information in the media about dietary carbohydrate requirements can appear complicated, the advice that health professionals provide to clients should be clear and simple: the majority of carbohydrate in the diet should come from a nutritious mix of whole-grain, real food carbohydrates (oats, breads, pastas, cereals), vegetables, fruits, nuts, and seeds. Reserve simple carbohydrates (sugars) for targeted use to fuel performance before, during, and after vigorous exercise.

Nutrition messaging in the media is constantly at our fingertips. Sometimes that advice aligns with scientific evidence, while other times it conflicts – often causing confusion around what to do to meet personal nutrition needs. This is certainly true when it comes to nutrition recommendations surrounding carbohydrates. Nutrition experts experience an uphill battle in their efforts to explain carbohydrates to the public.

Consumers hear various terms and phrases in discussions around carbohydrates, some of which have limited scientific support: - good carbohydrates, bad carbohydrates, simple carbohydrate, complex carbohydrate, refined carbohydrate, unrefined carbohydrate, low-carbohydrate diets, high-carbohydrate diets, no-carbohydrate diets, added sugar, sugars that are bad, sugars that are good, when to eat carbohydrate, when to avoid carbohydrate, whether or not carbohydrate causes fat gain, and why soluble and insoluble fibers are important. When discussing carbohydrate recommendations with active individuals, a sports health professional’s role is to dispense clear, accurate, and useful advice.

Although information in the media about dietary carbohydrate requirements can appear complicated, the advice that health professionals provide to clients should be clear and simple: the majority of carbohydrate in the diet should come from a nutritious mix of whole-grain, real-food carbohydrates (oats, breads, pastas, cereals), vegetables, fruits, nuts and seeds. Reserve simple carbohydrates (sugars) for targeted use to fuel performance before, during, and after vigorous exercise.

Carbohydrates: the body’s preferred energy source

Our body’s cells require energy from glucose, which comes from carbohydrate found in the diet. We consume carbohydrates in foods and beverages as simple sugars, starches, and non-digestible fibers. All of the carbohydrates we consume—whether from a soft drink, a piece of fruit, a whole-grain slice of bread, or an energy bar—are digested in the small intestine and absorbed into the bloodstream as simple sugars, such as glucose, fructose and galactose.  Starches, like pasta, rice and grains, are nothing more than large groups of glucose molecules that may take more time to digest and absorb, providing sustained energy release. The starches found in whole foods also contain vitamins, minerals, and fibers, whereas foods high in simple sugars, such as candy, soft drinks, sports drinks, energy drinks and desserts, typically are low in these nutrients.

All carbohydrates contain calories — 4 kilocalories (kcal) per gram — that can be used to fuel cells in the body, including those in the brain and muscle tissue. Glucose is essential for normal brain function and to fuel active muscles. Under normal circumstances, our brains use carbohydrate (glucose) to produce ATP energy.  Whenever our muscles are active for more than a few seconds, glucose is also the preferred fuel. The greater the exercise intensity, the more reliant muscles become on glucose as fuel. This is one reason why low-carbohydrate diets are not recommended for active people.
 

Our cells need a steady supply of energy to support day-to-day activities. Fortunately, our body is well-equipped to maintain a consistent level of blood glucose (blood sugar). Glucose is stored in the body as liver and muscle glycogen. The glucose stored in the liver is constantly used to ensure that blood glucose does not drop too low. Carbohydrates in the foods and beverages we consume also help maintain blood glucose. Examples of carbohydrates that fuel everyday brain and muscle function include whole-grain cereal for breakfast, a whole-grain peanut butter and jelly sandwich for lunch, a CLIF BAR^® Nut Butter Filled Energy Bar for an on-the-go snack, and a dinner of lean meat, vegetables and fruit.

When it comes to performance, consuming carbohydrate fuels active muscles before and during exercise and restores muscle and liver glycogen after exercise.  Targeted use of rapidly absorbed, simple carbohydrates helps people feel energized before workouts, work harder during exercise, and recover faster - all good things for those who regularly exercise. Examples of carbohydrate-rich foods that support active occasions include fruit before a workout, a couple CLIF^® BLOKS™ Energy Chews during activity, and trail mix or a whole-grain sandwich post-exercise.

Matching carbohydrate intake to activity level

Active people expend more energy than sedentary people and consequently eat more calories. Most of the energy (over 50% of total daily calories) should come from nutrient-dense, real-food carbohydrates found in whole grains, vegetables, fruits, nuts and seeds.  While there is no clear definition of “good” or “bad” carbohydrates, there are “more” and “less” nutrient-dense carbohydrate foods. As is true with excess energy from any macronutrient, consuming excess calories from carbohydrate can contribute to weight gain, whereas not enough carbohydrates in the diet can hinder performance. Resources such as the Active Nutrition Guide can help you develop custom nutrition plans to best support the daily energy and nutrient needs of your clients.

The Active Nutrition Guide is a compressive resource that explains the role of food in fueling healthy, active bodies, helps you calculate calorie and macronutrient needs depending on day-to-day intensity, frequency, and duration of activity, and includes case studies that showcase how to translate those calculations into real-life meal plans. The Active Nutrition Guide is also accompanied by a series of modules that provide activity-specific nutrition advice from sports nutrition experts, alongside real-world tips from athletes. Currently, modules are available for running, cycling, soccer and hiking.

Helpful reading

Burke LM, Ross ML, Garvican-Lewis LA, et al. Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. Journal of Physiology. 2017;595(9):2785-2807.

Clif Bar Active Nutrition Guide. https://www.clifbar.com/article/feeding-and-inspiring-active-lifestyles

Hawley JA, Leckey JJ. Carbohydrate dependence during prolonged, intense endurance exercise. Sports Medicine. 2015;45 Suppl 1:S5-12.

Helge JW. A high carbohydrate diet remains the evidence based choice for elite athletes to optimise performance. Journal of Physiology. 2017;595(9):2775.

Institute of Medicine. Dietary carbohydrates, sugars and starches. Dietary Reference Intakes for Energy, Carbohydrates, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: National Academy of Sciences; 2005:265-338.

Murray B, Rosenbloom C. Fundamentals of glycogen metabolism for coaches and athletes. Nutrition Reviews. 2018;76(4):243-259.

Thomas TD, Erdman KA, Burke LM. Nutrition and athletic performance. Medicine and Science in Sports and Exercise. 2016;48(3):543-568.

About the Author: Bob Murray is an exercise physiologist and Fellow of the American College of Sports Medicine.  Dr. Murray was a cofounder of the Gatorade Sports Science Institute and served as its director for 23 years (1985-2008).  Since 2008, Bob has consulted with companies large and small, helping apply knowledge in exercise science and sports nutrition to meet their needs. As a member of the Clif Bar & Company Nutrition Advisory Council, he uses his nutrition and sport science expertise to support Clif’s commitment to providing sustainable, nutritious food for athletes and active people.

About Clif Bar & Company: Clif Bar & Company crafts nutritious and organic food to feed and inspire adventure, including CLIF BAR® energy bars; CLIF Kid® energy snacks and LUNA® nutrition bars. Family and employee-owned, the company is committed to sustaining its people, brands, business, community and the planet.