Have you ever heard of or experienced a "sugar crash"? It is the tired feeling you get after eating a carb heavy meal. Energy drink manufacturers and coffee houses love these because it is good for business. What happens in the body after a carb heavy meal is there is a big spike in blood glucose thus a high insulin response. The insulin quickly gets all the glucose where it needs to be but because the insulin response was so great it remains in the blood for a while after it's job is done. The body gets a feeling of tiredness because of the perception that the insulin is still there but it has no energy to put away. These crashes lead to more carb cravings thus the viscous cycle of a carbohalic is continued.
In summary, ingested carbs = raised insulin = stored fat. (Unless you are a highly competitive athlete expending a lot of energy)