The problem with carbs is this, they break down into sugar (glucose) in the blood, and your pancrease secretes insulin to shuttle the sugar out of the blood to the liver then muscles for storage. If there's an excess of glucose that isn't burned off immediately and your glycogen stores are filled, the carbs are actually stored as bodyfat through de novo lipogenesis. Even if this doesn't happen, just the fact that when insulin levels are raised, fat burning comes to a stop. Anyway, the CKD and other low carb diets deal with this problem very well, but even the Zone diet, which allows 40% of its calories from (low glycemic) carbohydrates can prevent one from getting fat. Hope this info helps u out.