Altitude

One of the challenges of backpacking in the high Sierra is altitude sickness. While it can get very serious -- high-altitude pulmonary edema (HAPE) and high-altitude cerebral edema (HACE) -- for most people, it comes in the pretty standard forms of huffing and puffing while hiking uphill, headache, loss of appetite, and nausea.

I've had some trips cut short because of altitude sickness (either mine or someone else's), and I've thrown up a lot over the years while backpacking, so "solving" this was a big thing for me. Here's what actually worked.

Acclimation

I was already going on a high altitude day hike the day before my trips. Living in L.A., there are some great options, my absolute favorite being Mt. Baden Powell, which tops out over 9,300 ft. but doesn't take all day to hike (important since I also need to get home and pack). Easier options include Mt. Waterman (about 8,000 ft.), or Icehouse Saddle (7,500 ft.). A harder one would be Mt. Baldy (10,000 ft.), which is just too long and strenuous for me when I have so much else I need to get done that day.

Unfortunately, while these hikes undoubtedly helped, it wasn't enough to keep me from throwing up.

Food

This was a HUGE lightbulb moment for me. What I ultimately realized is that what I was experiencing wasn't necessarily altitude-induced nausea; rather, the altitude was causing loss of appetite, which meant I was barely eating anything at breakfast, which meant I was hiking big 10-mile days on an empty stomach. And I'm absolutely the kind of person who throws up when exercising on an empty stomach.

What I needed to do was eat as much as possible before and during hiking, when I didn't want to eat anything at all.

I started experimenting with different breakfast options, and discovered that none of them were quite plain enough to choke down. What ended up working best for me was fry bread. (I use the basic version of the recipe in the link and downsize it for one: 1/2 cup flour, 1/2 tsp baking powder, and a generous 1/4 tsp salt, plus a tablespoon of olive oil) This does mean carrying a frying pan (the MSR Quick Skillet), but that 6 ounces saves me a lot of stomach trouble, and means I also get to have quesadillas for dinner one night (so good), so it's worth the weight.

I also make a hot chocolate for breakfast -- drinking calories doesn't upset my stomach for whatever reason, and a good sugar rush helps get me going on the trail.

With both, that's 485 calories, and 3.7 ounces. A good start.

My on-the-trail snacks needed upgrading, too. The trail mix had to go -- it turns out that eating nuts on an empty stomach was also triggering my nausea. So I swapped in pita crackers.

And Kind bars and other chewy bars were also hard for me to get down, so I traded them in for those dry Nature Valley crunchy bars (Oat and Honey, Peanut Butter, and Maple Brown Sugar).

That's another 320 calories, and 2.5 to 3.0 ounces.

In an ideal world, I'd be eating more than that on the trail, but in the real world, that's already choking down more than I really want, and it's enough to get me to camp without throwing up, so I'm calling that a win. Once at camp, I eat a big hunk of cheese and have a lemonade, which gets me back to feeling good.

Exercise

To be clear, being physically fit does not prevent altitude sickness. However, getting into decent hiking shape may mean your body is working a little less hard to get through those miles, and if you have a two-pronged problem, like I did, then that may make a difference.

I'm no one's idea of an athlete, but getting a solid hike in every weekend before a trip, and doing the last one or two of them with a weighted pack, does get my heart, lungs, and leg muscles in something like good-enough shape. It can't hurt, at any rate.

Will this work for you?

I don't know. But I will say that the two big signs that led me to this solution were that (1) I felt terrible while hiking, but after I sat a while at camp, and ate some more snacks, and ultimately had dinner, I started to feel fine again (I still had loss of appetite, but I was only throwing up while, and shortly after, exercising); and (2) even on day 7 of a trip, it wasn't getting better -- I never acclimated, and I even got worse as I kept getting down very little food and pushing my body hard.

So if your body objects to hard exercise on an empty stomach even at sea level, and altitude is suppressing your appetite, then maybe consider experimenting with your food choices while on the trail. It helped me a lot, and maybe it will help you, too.