The logical answer to LNT and ultra-light is no-cook meals. Hot meals are optional, not a necessity. I do not think LNT and fires are necessarily at odds. I think the reason most people do not cook on fires is not LNT but that fires, done properly, are really time consuming. Also, does LNT refer only to the land we hike on? What about the impact of the technology needed to make gas cartriges or white gas? Every living thing leaves a trace. You are fooling yourself if you think you leave no trace by using artifical fuel. To me the problem is over-use, pure and simple. Put 20 people a day on any given campsite, and there will be impact, whether they use stove or fires. Second problem is that because very few people nowadays use fires, few people know how to make a good small cook-fire and clean up all evidence of the fire once they leave ths spot.