The simple act of eating carbohydrates will not cause weight gain. Eating too much carbohydrate (or fat or protein) can lead to weight gain. The recommendation is to get at least 45% of your calories from carbs. Carbohydrates are essential for good health and are the body's preferred source of energy. They include all bread, pasta, rice, fruits, vegetables (especially starchy ones), milk and sweets.
The key to managing your weight is balance. Instead of downing a big plate of pasta or rice, a pint of ice cream or a bag of chips, choose healthy carbs like whole grain bread, wild rice, quinoa, beans, sweet potatoes, melons and berries. Practice portion control at every meal. Grains should cover only a quarter of the plate. Half the plate should be fruits and/or veggies leaving the final wedge for protein.