This comes directly from my "Professional Baking" textbook. It's the 4th edition by Wayne Gisslen page 14-15 (if you are interested.)
"Staling begins almost as soon as the baked items are taken from the oven. There are, apparently, two factors in staling. The first is loss of moisture, or drying. This is apparent, for example, when a slice of fresh bread is left exposed to air. It soon becomes dry to the touch.
The second factor is a chemical change in the structure of the starch. This process, called starch retrogradation, occurs even when little or no moisture is lost. This means that even a well-wrapped loaf of bread will eventually stale.
Chemical staling is rapid at refrigerator temperatures, but it nearly stops at freezer temperatures. Thus, bread should not
be stored in the refrigerator. It should be left at room temperature for short-term storage or frozen for long-term storage."
There are 4 main techniques to slow staling... protect the bread from air... warming in oven right before serving... adding moisture retainers to the recipe (fats and sugars)... freezing. Adding more fats and/or sugars shouldn't really be an option if you are trying to be healthier, and explains why some breads have alot of added sugar. Heating the bread in the oven only really helps if it's a chemical stale, but this should only be done before eating since it will pull more moisture out of the bread.
(Did I mention I want to be a pastry chef?
Hope this helps!