To me, this looks like only a pile of marshmellows. Though I get your concept from your title, thats it, its just blah. Next time, try to find a creative way to show how a subject can be how it can be. Such as, instead of a pile of marshmellows that looks heavy instead of 'light', stick some feathers in the sides of one and photography it with the sky behind it. It shows that it really can be lite as air.
A fun concept, but I think you need to work on (ironically enough) the lighting to make your shot more appealing. Maybe making it black and white? As it is, it's not a bad photo, just not much to look at. I'm not voting in this challenge. Just wanted to leave a few comments for some folks. Good luck.