All of this pursuit of light weight backpacking has people figuring out what they can possibly leave behind to keep weight down. I get it. But one thing I have to wonder is how people manage to travel without any change of clothing whatsoever for hikes of 3 or more nights. I am particularly concerned about underwear.

Just in normal outdoor daily activity I find that getting sweaty irritates me to the point that I would not even think about not changing the boxers. And yet I have read more than enough light and ultra light lists of gear that advocate not carrying any extra clothing whatsoever even for longer hikes.

How do people deal with this situation? Am I unusual in needing to take care of hygene in that area? I know that everybody seems to be resigned to having plenty of BO after multiple days of hiking. But it is one thing to smell and another thing to have your hiking get painful due to irritation.

If it's worth the weight to you, bring it.

You could always bring a pair to wear and a pair to wash (and hang somewhere to dry, like the outside of your pack [but beware getting snagged in brush] or from the roof of your tent overnight). Spare socks are also a common item, either a day pair and a night pair, or, again, one to wash and one to wear.

Here's how I deal with it.

First, I wear some of those unreasonably expensive boxers made of a silky polyester material. These don't absorb the sweat so much, but tend to wick it and allow for less irritation from dampness. Cotton just doesn't cut it in this application.

Next, if it is at all humanly possible, I wash myself (water only, no soap!) at the end of my hiking day, as part of my routine for making camp. I carry a synthetic washcloth for this purpose. When I wash myself I also wash my dirty socks and put on a clean pair. The clean pair are those I wore and then washed the day before, giving them a full 24 hours to dry out. If they are not dry by morning, I safety pin them to my pack so they air out and dry as I hike.

Lastly, I own two pair of those unreasonably expensive boxers, giving me the option to wash and alternate them in the same way I do my socks. I don't always. Washing up is often good enough. But this last option might suit you best.

I go out as long as 10 days with only one change of socks, which get rinsed out every day. My clean clothes (and a package of moist towelettes) stay in the car to change into when I get back to the trailhead. My undies are synthetic and dry in an hour, so if I have to rinse them out, no big deal. In fact, if I shake them well and then put them back on, they dry with body heat in a half hour. I take a 2 gallon zippered freezer bag for a "washing machine." I don't use soap, just rinse 2-3 times to get most of the dirt out. Of course the waste water should be dumped a couple hundred feet away from any water source.

In case of horrendous disaster (spilled food all down my front?), all my clothing is lightweight synthetic, so I can at least rinse most of it out by the above method.

Some guys (but not, usually, we girls) go "commando" with no underwear at all. Even ladies did that a couple hundred years ago--in the days of long skirts, of course.

I also use the "laundry" freezer bag if my hiking shirt/pants/socks are wet. I seal them inside the bag and put the bag in the bottom of my sleeping bag. (Wet clothes in the sleeping bag will compromise the insulation, particularly down.) They don't get dry, of course, but at least they are warm when I put them on the next morning--and, again, dry quickly with my body heat.

I do sponge myself off in the tent at bedtime (with lukewarm water left after preparing my dinner), so I don't get too grubby. And remember, everyone else out there has that "backpacker aroma," too!

One popular brand of those "unreasonably expensive" undies is Ex-Officio. They have both men's and women's. I bought some in 2009 and liked them so much I wear them every day--and the ones I bought 6 years ago are still in good shape! They last long enough to be worth the money.

+1 on the "unreasonably expensive" synthetic underwear, though mine are boxer-briefs rather than boxers. My wife found a bunch for me at an outlet store, and they're my go-to undergarment on a daily basis, not just hiking. They perform way better than typical cotton underwear.

I have seen some of that "unreasonably expensive" underware in local stores. The first time a saw a package of boxers with a $20 or more price tag on it I almost choked when I noticed there was only a single pair in the package. I may have to break down a buy a pair or two but I sure hope I can catch a sale somewhere.

One of the very few "subsystems" I have dialed in is clothing, and I strive to not sleep in what I hike in. I'm more comfortable and importantly, can rinse out key items like tshirt and boxer briefs so they'll be dry and kinda clean the next morning.

Even if I slept in my hiking clothes, all the insulating layers and the rain gear are in my pack anyway, so there's not much duplication at all.

On that (luckily) rare night when I roll into camp after dark, set up, eat and crash, I might be too tired to bother changing at all. Usually regret it the next morning.

I only have a extra clean shirt, socks and underwear. Will have to check out whatcha all are calling expensive underwear though. Outer layer in the summer is only a light, down jacket, about 8 or 9 oz. is all I need for the Sierra.
Duane

Me, too - exactly like you.

Try a pair of under armor stuff. I work outside. All day . It gets hot here in Texas I love them best 20$ I've ever spent

Everyone's a bit different on this, with of course no single right answer.

What works for me is a pair of lightweight shorts and a very light synthetic t-shirt as "town clothes", i.e., what I wear when washing clothes when I'm in town to resupply and shower, etc. The shorts also serve as sort of emergency backup underwear, but I've never used them that way. These I just carry but rarely use in any way "on trail".

One or two pairs of liner socks to change into is enough for me, depending on conditions; rarely I'll wash a pair on the trail but mostly not. One pair of underwear (total, not extra). Once in a while chafing will have me go commando for a while until it clears up. I'm happy hiking either way.

One shirt, the one I wear. In colder weather maybe add a thin long sleeved base layer, but almost certainly only for use at night, or possibly the early morning as well.
Definitely just the one pair of pants.
In colder weather, perhaps something like capilene-1 longjohns. Sometimes hike in these for a while in the morning, then change out of them as I warm up (want to put these away pretty dry for use again that night).

I sleep in the same clothes I hike in. Unless they get wet, in which case I wear less in the sleeping bag (town clothes if necessary) and then put the wet clothes back on in the morning.
If it's a pretty wet trip, it's nice to have a base layer shirt and long johns to wear at night when clothes are wet.

Sleeping socks (or down booties) in colder weather, dedicated to just use in the sleeping bag.

That's about it. I think part of the issue is just making a sort of mental shift about expectations, but perhaps personal body issues make a difference too for some. I don't wash on the trail at all, apart from my hands after using the toilet. A shower once a week or so is nice to have, but sufficient. Repeat for as many weeks as you're on the trip.

Again, I don't prescribe this as any sort of universal approach. From interaction with a number of friends and acquantances I do think that something along this line isn't unusual for long distance hikers.

I found inexpensive wicking base layers at Burlington Coat Factory - non brand name stuff but they work rather well. In the colder months, I skip the boxers altogether and wear the "Brand X" as long underwear. In the warmer months, I have wicking boxer briefs that hold everything in place. I bring a pair of cotton long johns (cold) or cotton boxer briefs (summer) for sleeping.

Over the course of several multi-day hiking trips and 2 multi-day kayak/camping trips, this system works quite well for me.

I like to carry 2 wet wipes for each day out and use them to clean the appropriate body areas. I use the personal adult wipes, which are a bit larger and made for bathing purposes. They don't dry you out, are available at Target, Walmart, etc, and an acceptable weight addition for the level of comfort they provide.

I carry NO extras. I jump in a creek or lake EVERY day immediately after hiking, no matter what the weather. Never use soap. I wash undies and go without until they dry. I have a 4 oz undershirt that dries quickly. It is first used as my "towel", then rinsed, and hung on a bush. If it does not get dry, it goes under the vestibule, and then next morning, I put on the damp shirt and it dries while on me. I rinse out wool socks every day- have three- one to wear, one to be drying while I hike, and one dry clean pair for sleeping. I hike in the west where we do not have the humidity of the southeast, so my situation may be quite different than yours.

If you are going to rinse out clothing in streams, be sure to double or triple rinse them at home. Most home washers DO NOT get all the soap out in a regular cycle.

Also, do not rinse out clothing in streams or lakes if you spray them with mosquito repellant.

Ditto, no extras. I rinse baselayer clothes daily...never using soap...

Are you ever out around people? What if modesty's a concern?

Ditto on the expensive non-cotton boxer briefs. They're all I wear anymore on and off the trail.

I always carry an extra pair of underwear and socks, even if it's only an overnighter. Hand sanitizer and body wipes are always in my hygiene kit. Campfire smoke kills B.O.

I try to keep my pack weight under 20 pounds so I hike in running shorts and a t-shirt. I use Smartwool micro light running socks. They are pretty durable and can be hand washed and dried overnight. you can also get a couple days use out of them. as such I only pack a pair of lightweight long pants and they smartwool base layer long sleeve shirt for colder weather and night time wear. so I don't have a change of clothes I just have a colder layer. I change into the cold layer for the evening and try to rinse off my shorts and t shirt so they can dry over the night. this has proved really effective for me in the summertime. the t-shirt is a North Face brand lightweight quick-drying fabric similar to Cool Max. They usually cost about $20. they don't hold order, they're as comfortable as cotton but dry pretty quickly.

I pack a pair of ice breaker wool briefs and a spare pair of smartwool socks as part of my cold layer. I sleep in the briefs and a long sleeve smartwool baselayer.in the morning I put on the mostly dry running shorts and t-shirt and previous days socks