False - Carbohydrates themselves are not fattening. If you eat too much of any food (carbs, protein or fat) you will gain weight. When calories eaten, regardless of the calories, are greater than the calories you burn during physical activity, weight gain occurs.
Carbohydrates are the primary source of fuel for the muscles and the brain. Protein provides less than 5% of the energy expended during physical activity. Carbs are the only fuel that can produce energy fast enough for powerful, explosive movement. If carbs are lacking in the muscles and blood, your body is forced to breakdown amino acids. This is a very slow process and therefore slows your response rate and reduces your energy level. Your brain will also use any available carbs first, leaving nothing for active muscles. So, your head will be into it, but your body won’t be able to keep up.
Some of the confusion regarding carbohydrates being bad for you comes from portion distortion in the servings that we consume. For example, most people treat a bagel as one grain serving when in fact, the amount of carbs a bagel provides is often equivalent to the same amount as in 4 slices of bread. Another example is pasta. A half cup of noodles is one serving and many of us can consume 5-6 times this amount in one sitting (not to mention along with garlic bread too). Carbs are not bad or fattening, but eaten in too large portions, can contribute to weight gain just like too much fat or protein.
Eating carbohydrate-rich foods with starch and fibre keep you performing smarter and longer without fatigue. Carbs are found in: breads, cereals, rice, pasta, potatoes, milk, yogurt, fruits and vegetables.