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Complex Carbohydrates…Not So Complex To Understand

By Abby Forman, MS, RD

Carbohydrates are your body’s main source of fuel. They are used exclusively by your brain (with the exception of ketones) and give us ready-to-use energy for high intensity athletic activity.  There are two kinds of carbohydrates, simple and complex.  Simple carbohydrates are those that only contain one or two molecules per chain (mono-, di-, and oligosaccharides). These include simple sugars like glucose, fructose, galactose, and their combinations like lactose.  They are easily digested and processed by the body leading to a quick rise in blood sugar (glycemic response).  Complex Carbohydrates or polysaccharides contain longer chains of sugar (starches) and non-digestible fiber. Because of this they are harder to digest and take longer to raise blood sugar.  These complex sugars help to keep our blood sugar stable over the day and avoid the mid-day crash.  The fiber found in them also helps with digestion, lowering cholesterol, and prolongs fullness. They should make up the “bulk” of your daily carbohydrate intake.  Simple carbohydrates work great for when blood sugar needs a boost, like right before and during longer intense activity (say a hard long run) when you don’t want something sitting in your stomach for a long time.  Check out these examples.



Simple Carbohydrates: table sugar, fruit juice, honey, molasses, maple syrup, candy, fruit jelly, etc.

Complex Carbohydrates: whole grains, whole vegetables, whole fruits, beans/lentils, etc.

Too much of anything can be a bad thing.  The same thing goes for carbohydrates.  Taking in more carbohydrates at a sitting than your body can process or use will result in storage for later as fat.  Each person has individual needs based on their gender, height, weight, age, activity level, and training cycle.  Spread out your carbohydrates over the day in a balanced fashion. Include a source of protein and fiber (such as non-starchy vegetables) at meals and snacks to aid in satiety and stable blood sugars.  Aim for about 0.5g of carbohydrates per pound of body weight in your recovery snack to be ready for your next run.  If you need help calculating your needs or have questions about nutrient timing, ask your sports dietitian.