Carbohydrates are molecules that have carbon, oxygen and hydrogen atoms. In nutritional terms, carbohydrates are one of the three macronutrients, the other two being protein and fat.
Dietary carbohydrates are composed of three categories: sugars, starches and fiber. A combination of these three carbohydrate categories provide our bodies with the energy we need to fuel our daily lives.
Energy is produced through the breakdown of sugars (glucose), which are then used as energy. Carbs can also be turned into fat, which stores energy for later use.
Some carbs are better for you than others. Choose to eat "complex" carbs over "simple" carbs, or "whole" carbs over "refined" carbs.
Whole or complex carbs are unprocessed and contain the fiber found naturally in the food. On the other hand, simple or refined carbs are highly processed and had the natural fiber removed or altered.
Of course, it is okay to eat simple/refined carbs from time to time. Eliminating them completely from your diet is not realistic for everyone.
In general, carbohydrates in their natural, straight from the source, fiber-rich form are healthy. In contrast, carbohydrates that have been processed and stripped of their fiber are not.
If you are unsure whether or not a carbohydrate is good for you, think of it this way: if it is a whole, natural, single-ingredient food, then it’s probably a healthy source of carbohydrates.
Instead of thinking of carbs as either “good” or “bad,” focus on eating whole and complex carbs over simple and refined carbs.
Below is a non-comprehensive list of foods that would be considered "good" (whole/complex) carbs and "bad" (simple/refined carbs).
"Good" (whole/complex) carbs: vegetables, whole fruits, nuts, seeds and whole grains.
"Bad" (simple/refined) carbs: soda, processed desserts (such as pastries, cookies, and cake), white bread and chips.
