"Carbohydrates are an easy energy source for your body. It is a much easier source than pulling fat out of storage. However, carbs burn up quickly. If you have been eating a diet high in carbohydrates, your body is "carb-adapted" and looks for them as its primary energy source. Therefore, if you reduce your carb intake, your body will ask you to feed it more by turning on cravings. Dietary fat – that you eat – is more accessible than stored fat…"
(Excerpt from I'm Low Carb. Shouldn't I ALSO Eat Low Fat to Burn Body Fat?: )