Calories are still important. If you eat more calories than you use you will end up storing some extra calories in your fat cells. If you need more calories than you consume then your fat cells will be forced to cover the difference. Fat does contain more calories per gram (9) than either carbs (4) or protein (4). So, IFing through breakfast can help you control your intake in the remaining two meals and therefore make it easier to maintain a calorie deficit and therefore to lose weight or to maintain your current weight.
Personally, I never eat breakfast and I find that once you get used to having or not having a meal at a given time that's what I tend to do anyway. Our body's tend to produce the hormone ghrelin when we're expecting to be fed, so if you never ate breakfast then you body wouldn't do that in the mornings. If you did your body would produce it in anticipation of having breakfast.
Combine that with the fact that eating removes one's body from a fasted state I eat most of the time by the lean gains approach of approximately 16 hours of fasting and an 8 hour eating window.