Second part of the question; Does your answer change if the fat type is unsaturated vs saturated fat?
Assume for this, carb source is fairly refined sugar such as in soda, white bread, in energy/granola bars, juices or high glycemic fruits. The type of things most people end up snacking on. Exclude fairly complex carbos (ex from low glycemic vegetables) for your answer, mainly because these are not readily accessible snacks for most people except for the most organized amongst us.
Also assume this is not during exercise and also you can assume that it is early enough in the day that what you eat early in the day may or may not affect your total calorie gain/deficit over the day (ie gain or lose weight).