It was an honest question though, and your statement was anything but clear for beginner like me. Let me put this in a real-world context:
You have a Nikon D3 and the Nikon D300. You have a photographer shooting birds reeeally far away. There is enought light for you to never use higher ISO than 1600. So what we have in the end is the following: two cameras which will have a very similar if not the same IQ performance in the given conditions (FPS are a different matter, but we'll have to agree that this doesn't have anything to do with the sensor), one will have a 1.5x crop and one will not. If both use a full frame lens, of course more of the image will be "lost" (meaning it will be not be on the sensor) on the D300, but you will still get a 12MP image, at a 1.5x zoom boost. On the D3 you will also get a 12MP image at the standard 35mm focal length.
Of course, if you are talking about loss as an absolute term, meaning that a part of the image circle is going to be lost (or cropped, if you prefer), then this is true for all SLRs, as I don't know any with round sensors (or round film, but feel free to correct me).