its not so much the coffee itself that is said to be an aid in fat loss, it's the caffeine.
Caffeine creates a thermogenic effect in your body, causing you to burn more calories and attain an increased metabolism.
Cappacino's are no good man. Lots of sugar and even if it has skimmed milk, its not recommended.
Butttt ... if you must have them ... have them right before workouts for the carbs and caffeine, for some extra edge