It is important not to carry too little. Not having gear can create more safety issues than benefit. The true success to ultralight backpacking is to hike with people who have STUFF!
I have noticed that since super lightweight backpacking has become popular I find more people on the trail wanting to borrow stuff from me. Many of them look like they are cold in the morning and hungry in the afternoon. If you use some common sense and lighten your load to a reasonable extent you will find you can comfortably do just as many miles in a day with thirty pounds on your back as people carrying half that weight.
Light weight hiking is not only restricted to backpacking. If you day hike you can also drop pounds just by thinking about what you really need to have along and what you may be able to replace with lighter gear.
One rule of thumb that does not always work is, "If I haven’t used it in a hundred miles I don’t need it." I tried that last summer while hiking the Great Divide Trail in Canada. I started out with great weather and no bugs. After a week on the trail I came in for a resupply and went through my gear so see what I might leave behind on the next section. I came across my bug repellent and thought, "I haven’t used this. There haven’t been any bugs."
I left my bug repellent and the little beasties devoured me for a week. It was like they had put out a newsletter and every bug in the Rocky Mountains knew I was fair game. No bug juice. Saved myself about 3 ounces. Actually I saved a lot more weight than that because the insects took at least a pint of blood and blood is heavy.
So my point is—don’t get carried away. Take what you need and trim what you can. Save weight on items that do more than one job. Example: a rain poncho that also works as a ground cloth. If you hike with others you can share the load with community items like the cooking gear, shelter and water purification equipment. The more you think about it the lighter you become and the lighter you become the more you are going to have to start looking down the trail for people with STUFF! —Keep Smilin’, Dick E. Bird