The biggest difference between complex and simple carbohydrates is the rate of which they are digested and utilized in the body.
In simple terms, complex carbohydrates have more glucose (sugar) molecules and take the body longer to breakdown. This is a good thing for weight loss! When you consume complex carbohydrates your body has to work to break down those individual sugars, giving you more sustained energy and fullness for a longer period of time. Complex carbohydrates can also be called "starches". These include sweet potatoes, brown rice, oats, barley, millet, corn tortillas.
Simple carbohydrates are also known as "simple sugars" meaning the body doesn't take very long to break down the one strand of sugar. This gives you instant energy, but unfortunately this energy isn't long lasting and you may feel hungry within an hour of eating simple carbohydrates. These include sugar, soda, cookies, chips and fruit (fruit is full of vitamins and fiber so it is okay!)