There is nothing inherently “bad” about carbohydrates (a.k.a. carbs) just like there is nothing inherently “bad” about fats. It is the type and quantity that can be a stumbling block for many people.
The primary function of carbohydrates is fuel used to create energy. Any excess fuel that is not used is eventually stored in adipose tissue (i.e., fat). Through digestive and metabolic processes, carbohydrates are broken down into glucose (a simple sugar). Glucose molecules are further broken down (via a process called glycolysis) generating ATP (adenosine triphosphate) and pyruvate molecules that are used to create energy.
Translation: Glucose is broken down into cellular gasoline and is the main source of fuel/energy for the body.
Complex carbohydrates are made up of multiple sugar compounds. Because they have many sugars molecules joined together they take a long time to digest thus providing long-term energy.
Simple sugars are comprised of one or two sugar molecules and are digested very quickly providing immediate, short-term energy.
In the weight loss industry carbs have erroneously been ascribed the label “bad.” Potatoes (or rice, bread, pasta etc.) are not inherently “bad,” however, if you have a sedentary lifestyle and eat lots of carbohydrates, any sugar that your body does not use for energy production will be stored as fat.
So what is a “bad” carb? In a nutshell, “bad” or unhealthy carbs are man-made, pre-packaged, processed foods that are loaded with added sugar, fat and artificial chemicals. Using the example of the potato, a baked potato is a much healthier choice than potatoes that are deep fried in oil and salted (either potato chips or French fries).
Source: DelPrete, A. A Wellness Revolution: It Starts with YOU! Albuquerque, NM: Anita DelPrete PhD, 2012.