They don't - if you don't overeat them. Carbohydrates are found in fruits and vegetables.
Emphasize on choosing a variety of fruits and dark green leafy as well as bright-colored vegetables which are loaded with antioxidants and fiber. In addition, carbohydrates are also found in grain products.
The American Dietary Guidelines recommend eating at least half the grains as whole grains - that's at least 3 servings of whole grains a day.
Many diet books blame a high carb diet for the obesity epidemics - it is simply not true.
We have been explaining to the public that it's not the carbs - it's actually the total calories that contributes to weight gain. If we eat more calories than we need to spend, we will gain weight - regardless of a high carb or low carb diet!