Carbs or carbohydrates, also known as “monosaccharides,” are defined as simple sugar molecules in the most basic form, and are the most active source of fuel while exercising. The most common monosaccharides are glucose, galatose, and fructose. When you have two or more monosaccharides that are larger carbohydrates these are referred to as “disaccharides.” Disaccharides are also called trisaccharides or polysaccharides based on the number of sugars. Carbohydrates are categorized by either simple carbohydrates or complex carbohydrates depending on the length of the sugar chains. Simple carbohydrates are simply sugars that are made up of just one or two sugar molecules. Complex molecules are made up by sugar molecules strung together in long, complex chains. These are found in foods such as: beans, whole grains, vegetables, etc. In order for carbohydrates to be used to the fullest, they must be digested to the monosaccharide form.

Glucose is the primary monosaccharide. It is important for mainly more endurance activities. The recommended intake of glucose for humans is typically 300-400 Grams of glycogen in the muscles and 80-100 Grams in the liver. The storage of glucose in the human body typically lasts sufficiently approximately 90-180 minutes while exercising unless working out at a high intensity. If working out at a higher level with more intensity, then the storage lasts around 30 minutes.

The Glycemic Index was developed for diabetic patients to control their blood sugar. It is defined as a system of categorizing foods based on the impact they have on blood sugar levels. The rates go off of foods rate of digestion, and tendency to increase blood sugar. The Glycemic Index rates from 0-100 with 0 being no blood sugar response and 100 being the maximum. There are some foods that are above 100, which would be considered rapid-digesting carbohydrates. A rate of 55 or below would be considered Low GI, 56-69 would be considered moderate, and 77 or above would be high. Foods with a lower glycemic rating would produce lower levels of peak insulin secretion, whereas high GI foods would increase the likelihood of body fat retention. Here is a Glycemic Index Values of Common Carbohydrate Source:


Carbohydrate Source Glycemic Index
Fructose 32
Lactose 65
Honey 83
High Fructose Corn Syrup 89
Sucrose 92
Glucose 137
Maltodextrin 137
White Sugar 142
Maltose 150
Trehalose 67
Maltitol 36
Xylitol 13
Isomalt 9
Sorbitol 9
Lactitol 6


There are different times when you should intake your carbohydrates. The three main times when you should have your carb intake would be before, during, or after working out. When taking in carbs before working out this can help preserve the muscle glycogen storage and extend muscle endurance. When taking in carbs before your workout it has been shown that it doesn’t matter whether your carbs are low glycemic or high glycemic. They are both equally important, and will get the same effect during your workout as long as blood glucose is maintained.

Carb intake during your exercise would be most important during high intensity exercising, or if your workout exceeds one hour. An example of when you would want to take in carbs during your workout is if you were doing a lot of cardio. This will lower your insulin sensitivity, and will drop your blood sugar. Glucose is absorbed effectively through the small intestine at a rate of 1 Gram per minute. The recommended intake of carbs during your exercise would be drinking 7.5-15 Grams of simple carbs (sugars) every 15 minutes or 30-60 Grams slowly every hour.

Eating carbohydrates after your workout or post-workout is considered the most crucial for nutrition intake, growth, and recovery. To get the most out of the carbs post-workout for recovery, it’s recommended to taken in glycogen the first 30-60 minutes after or post-workout because that’s when it maximized glycogen retention. If an intake of carbs within the first two hours of training glycogen resynthesis is slowed. Once carbs are taken post-workout one’s insulin sensitivity, amino acid transport, and protein synthesis is intensified. Post-workout protein and carbs maximize protein synthesis rates, retention of glycogen, and maximizes protein catabolism.


Llewellyn, William. William Llewellyn’s Sport Supplement Reference Guide. Molecular Nutrition LLC of Jupiter, FL 33458, 2009. 20-22.

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