Carbohydrate loading may give you more energy during an endurance event. You may feel less fatigued and see an improvement in your performance after carbohydrate loading. But carbohydrate loading isn't effective for everyone.
Other factors can influence your athletic performance or interfere with the effectiveness of your carbohydrate-loading strategy, including how fit you are, how well you hydrate and how intensely you exercise. Even with carbohydrate loading, you still may feel muscle fatigue.
If you're a man, a carbohydrate-loading diet can increase the levels of glycogen stored in your muscles from 25 to 100 percent of your normal amount. Fewer research studies exist about carbohydrate loading in women, and they've yielded mixed results. A woman may need to consume more calories than usual during carbohydrate loading to get the same benefits as a man does.
Despite carbohydrate loading, you still need to replenish your body's energy during endurance events to maintain your blood sugar levels. You can do this by periodically consuming sports drinks, gels, or bars, fruit, or hard or chewy candies during your event at the rate of 30 to 60 grams an hour. And don't forget to eat carbohydrate-rich foods after your endurance event, too, to replenish your glycogen stores.
Carbohydrate loading isn't right for every endurance athlete. It's a good idea to consult your doctor or a registered dietitian before you start carbohydrate loading, especially if you have diabetes. You may also need to experiment with different amounts of carbohydrates to find what works best for you.
A carbohydrate-loading diet can cause some discomfort or side effects, such as:
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- Weight gain. Much of this weight is extra water, but if it hampers your performance, stick to your training diet rather than carbohydrate loading.
- Digestive discomfort. You may need to avoid or limit some high-fiber foods one or two days before your event. Beans, bran and broccoli can cause gassy cramps, bloating and loose stools.
- Blood sugar changes. Carbohydrate loading can affect your blood sugar levels. If you have diabetes, monitor your blood sugar during training or practices to see what works best for you. And talk to your dietitian or doctor to make sure your meal plan is safe for you.
See more In-depth
- Basics of carb-loading for sports performance. Academy of Nutrition and Dietetics. http://www.eatright.org/resource/fitness/sports-and-performance/fueling-your-workout/basics-of-carbohydrate-loading-for-sports-performance. Accessed Aug. 31, 2015.
- Body composition and nutrition for sport. In: Wilmore JH, et al. Physiology of Sport and Exercise. 4th ed. Champaign, Ill. Human Kinetics; 2008.
- Duyff RL. Athlete's guide: Winning nutrition. In: American Dietetic Association Complete Food and Nutrition Guide. 4th ed. Hoboken, N.J.: John Wiley & Sons; 2012.
- Zoorob R, et al. Sports nutrition needs before, during and after exercise. Primary Care Clinical Office Practice. 2013;40:475.
- Jeukendrup AE. Nutrition for endurance sports: Marathon, triathlon and road cycling. Journal of Sports Sciences. 2011;29(suppl):S91.
- Deldique L, et al. Recommendations for healthy nutrition in female endurance runners: An update. Frontiers in Nutrition. 2015;2:17.
- Carbohydrate and exercise. In: Dunford M. Sports nutrition: A practice manual for professionals, sports, cardiovascular, and wellness nutritionists dietetic practice group. 4th ed. American Dietetic Association. 2006.