Altitude and (water) weight loss - is it a thing?
April 9, 2019 9:16 AM   Subscribe

Does traveling to higher elevation cause super-quick (water) weight loss? Or, wtf happened to me and how can I make it happen again?

In 2017 I spent about 12 days in the southwest. It was the first time I’d spent any significant amount of time above ~2500 feet. On this trip, the highest I went was ~7000 feet; I traveled up gradually from about 2000 feet and then slowly traveled back down again before flying home.

On day 3, as I was walking around a town at 5500 feet, I noticed my 15-yr-old jeans seemed looser than they’d ever been. As the trip went on, they (and the one other pair of pants I brought) became even looser. It was really dramatic; I looked slightly ridiculous, like a curvy woman dressed up as a little urchin boy. It was as if, after years of struggling to lose those last 5-10 lbs, I was suddenly magically smaller without even trying. At one point, I thought my jeans might simply have stretched out, so I washed and dried them on hot and put them on straight from the dryer. They were still just as loose.

I maintained this weight loss throughout the trip, but after I got home, I soon returned to my previous size. Ever since then, I’ve been dreaming of getting back to the size I was during that trip. I’ve also been Googling the heck out of altitude + weight loss. I have found a bunch of articles about studies. But the subjects in one study mentioned in that link were obese men at 2650 meters (over 8600 feet), and in another, men in a simulated 40-day ascent of Mt. Everest. Also, it seems their weight loss was related to diminished appetite, which I don’t think applies in my case because I ate about the same.

-Background: For years I've been stuck at a weight/BMI that’s technically “normal” but that because of my body type and where I store fat, is physically uncomfortable and not very attractive. I’m much more comfortable when I’m 5-10 lbs lighter. What may be more relevant is that I retain water like crazy; if I so much as glance at an olive I puff up like a new foam mattress just removed from its packaging. (And, yes, I typically drink PLENTY of water, eat lots of hydrating foods like fresh fruit & vegetables, and eat very low sodium, both at home and when traveling.) I often say that I don’t even need to lose weight, I just need to be poked with a pin to let the water drain out. And that’s what it felt (and looked) like happened on this trip. I didn’t have access to a scale, but the change in the fit of my pants (not so much my tops; I don’t bloat in the arms) and the way I looked was obvious.

-Diet: I track my food using Cronometer every day and have counted calories using some method or other for as long as I can remember. So I know exactly what I ate on this trip and I know that I ate roughly the same number of calories as I do normally. I drank my usual amount of water (and as usual only drank herbal tea and juice other than water.) There was one notable difference in how I ate: while I usually have one serving of dark, non-dairy chocolate every day, and a cup of decaf coffee most days, I cut those out on this trip. That meant my daily fat percentage went from ~10% to about ~4% and I consumed zero caffeine. To test whether this is what caused the weight loss, I recently repeated almost my exact diet from the first seven days of the trip. There was no change, and in fact I may have gotten bigger.

-Physical activity: I was about as active on this trip as I am normally, whether at home or traveling. My usual exercise is simply walking.

-Appetite: It's possible my appetite was very slightly less on this trip than it is at home, but I still ate the same amount of calories I eat normally, so though I may have felt slightly less hungry, I didn’t eat less food.

-Timeline: I should stress how quickly this “weight loss” happened. While I might have guessed that lowering my daily fat percentage could lead to a tiny weight loss over the 12 day period, it actually happened much quicker. It was quite apparent as soon as day 3, and I noticed it had increased considerably by day 5. The day I washed my jeans was, I think, day 7. As I understand it, one can’t really lose fat this quickly. So I think I probably just lost water, which as I mentioned is what I’ve always wanted. It really felt and looked as if 5 - 10 lbs of puffiness was just drained off me.

-Also, I think I can say it's not related to the dry air or some other magical southwestern phenomenon, because I spent about 4 days in Tucson (only 2300 feet) last year, and didn't change size at all.

I feel silly asking this because I think if this was really a thing, it would be common knowledge. I mean, no one ever says “I need to fit into this dress by the weekend, brb I’m getting on a flight to Denver.” (Or do they?) I’m basically looking for either a scientific explanation or relevant personal anecdotes, but mainly I want to know how I can reproduce this effect here at sea level. (Because as much as I love the southwest, I don’t want to move there just to look good in pants.)
posted by DestinationUnknown to Health & Fitness (9 answers total) 3 users marked this as a favorite
It might be the change in the water you drank. Your local water might be so hard, it doesn't metabolize well, within you. Or there might be contaminates that make your kidneys malfunction. I lived at that altitude, but drank spring water light in minerals. Everyone in Utah is not lean. But your sudden increase in kidney function is something to look in to.
posted by Oyéah at 9:24 AM on April 9

Was the food you were eating there accidentally more low-carb than you're used to? What you described is what happened to me within days when I went Keto, and it hasnt let up. First it was all water weight and the loss of all my bloating, and then it just continued. Seems like I'm eating the exact same amount, same activity level, but suddenly my clothes got so loose I had to buy new ones and I was simply never all puffed up. I should add I do keto for epilepsy not weight loss, but the dramatic de-puffing and weight loss and major ab-situation cannot be denied.
posted by thegreatfleecircus at 9:34 AM on April 9 [1 favorite]

High elevation does change your blood chemistry somewhat, but the main thing if you are not well acclimated is that you dehydrate much faster than at lower elevations.

So, if you were drinking water at your usual rate, you were still losing it much more quickly. 5-10lbs is roughly a gallon of water (8lbs), so not a huge difference. I used to see the effect when I went from ~5000 feet up to 10,000 for work. Give it a few weeks, and you'll get the weight back, unfortunately.

This effect was probably the number one cause of most of our SAR calls - people would underestimate how quickly elevation dehydrates you, even at cooler temps, and then suffer effects like altitude sickness - which can turn into a HAPE and HACE if not treated.
posted by Pogo_Fuzzybutt at 9:38 AM on April 9 [7 favorites]

-Physical activity: I was about as active on this trip as I am normally, whether at home or traveling. My usual exercise is simply walking.

It's harder at altitude, though. My guess is extra exertion plus you were probably drinking substantially more water if you were appropriately coping with the altitude change/lowered ambient humidity.
posted by internet fraud detective squad, station number 9 at 9:39 AM on April 9

Sounds like water weight. Water is a funny thing at altitude. Relative humidity, sun exposure and intensity, alcohol intake, all these things can have a strong effect. I live at 8000 feet in a high desert climate and regularly hang out at 10-11k feet. Used to live at sea level. All of this is anecdotal...

I can never drink enough water here. Everyone who visits us gets the same suggestion: it's dry here and the sun is intense. Water on the ground evaporates very quickly. Your body is working harder than it normally does, not just physical exertion from being out and about in the sun, but also making more new red blood cells to make up for the lower oxygen level. You think you drink enough water but you don't, so drink it any chance you get. My roommate who moved here from sea level was up to 1-2 gallons a day and still wasn't getting enough, until his body sorted itself out.

Another thing most people don't think about is gassiness. For me, gas seems to just sit in my guts and never leave when I'm at low altitude. Much easier to pass at higher altitudes. :)
posted by Snacks at 9:42 AM on April 9 [1 favorite]

So, if you were drinking water at your usual rate, you were still losing it much more quickly.

Yes, this is my other guess, but I feel like you would have noticed substantial discomfort w/in 12 days and upped your intake? And if you keep weight at the belly also consider whether you were, uh, more regular than usual.
posted by internet fraud detective squad, station number 9 at 9:42 AM on April 9

This is actually pretty common, and to quote this linked article from Journal of Wilderness Medicine: it is well known that weight loss occurs with high altitude exposure. I live in Denver - already pretty high! - and this happens to me frequently when I go up in the mountains, but I have to go up much higher because I grew up at higher elevations and because my body has adjusted to "the mile high city" - 8000 feet isn't going to be enough. I DO like to joke that if I need to lose 2-3 pounds to fit into a special occasion dress I just have to go spend the weekend backpacking. And it does happen quickly!

Part of it, for me, is that my appetite does diminish and I am more physically active when I go higher. I do not understand fully why my appetite diminishes, but if I ascend more than 5000 feet it can diminish to the point where I don't want to eat breakfast, which is my favorite part of the day. And even when I'm forcing myself to eat, I'm not, you know, scraping down the plate like I would normally.

But there's another part, which is why I've accidentally ended up starving myself from time to time when I've had a really high fat diet in the mountains; this is my understanding of it, which has to do with oxygen availability and how well your body can metabolize calories, especially fat, because your body needs more oxygen for fat. (Which is why, if you are going to spending a lot of time and energy at high altitudes, carbs should be your food of choice if you don't want to lose weight.) You have less oxygen at higher altitudes, so your body doesn't metabolize the calories you're eating as well as it could. To quote the article I just linked:
"At an altitude of roughly 4,000 meters, every breath of air contains about 40 percent less oxygen than it would at sea level. Under those conditions, carbohydrates are the logical energy source. That's because carbs can supply 15 percent more energy for the same amount of oxygen in comparison to fats."
I realize you noted you were eating less fat than normal - I'm just using that as an example of how oxygen intake does impact how you take in calories; basically even if you are eating relatively the same, your body isn't taking in the calories as it would normally. (I'm hoping someone will come in with actual medical knowledge and explain this better!) The Journal of Wilderness Medicine article I linked to at the beginning notes that "hypoxia alone could contribute to lower energy intake" and subsequent weight loss, even with high carb diets as they used in their study. But what I *also* understand about this is while there are some logical hypotheses out there, there aren't a lot of studies that fully explain or study just "normal" people who aren't more physically active, or aren't contrasting location dependent subjects who live permanently at low or high. In other words - most studies don't really center around people like us.

However, there IS a lot of research on high altitude and exercise, and if you look up "hypoxia and exercise" you will discover entire books on the subject, and that may have something to do with your situation even if you're weren't exercising more than you normally do.

And hydration has a lot to do with it, as noted. Elevation and water intake IS a funny thing; that's why hangovers or drinking just a little bit of alcohol at higher elevation can be brutal. Your body simply needs more water at higher altitudes; you lose water from your lungs just by breathing thanks to the drier air. And altitude has a diuretic effect. And of course water intake/use/retention is affected by your metabolism, etc., and your entire digestive system is also affected by water and altitude, etc., - it's a nice little system in which everything is affected by everything else. So all in all, it's probably a combination of factors!

I will say that moving someplace isn't a solution, because your body will adjust eventually. And it doesn't take long to gain back that extra weight. In fact, if I do go up in the mountains for a week or longer and lose more than a pound or two, when I come back I'm always super hungry. This happens often and quickly enough to me that I've learned never to buy clothes at elevation if I've been up in the mountains for a few days, because it's guaranteed that I will gain those pounds back within a week of being back home and those clothes won't fit.

As to your question of reproducing the effect - that's difficult. My only thought would be to reverse it - not knowing what you have tried in the past, of course - if you have a low fat diet at lower elevations, have you tried significantly upping your fat and protein? (Within medical reason, of course!) Or upping your physical activity level so as to make your body work harder and burn more oxygen and use more water, especially in an aerobic way like low intensity workouts?
posted by barchan at 10:38 AM on April 9 [6 favorites]

I had a similar experience during a trip to the mountains in CO (my hair also looked better than it ever had in my life!)

As for this: For years I've been stuck at a weight/BMI that’s technically “normal” but that because of my body type and where I store fat, is physically uncomfortable and not very attractive. I’m much more comfortable when I’m 5-10 lbs lighter.

I also retain water very easily, on top of gaining weight easily in my midsection. I find that more than looking unattractive it can be about feeling physically uncomfortable, as you pointed out. Feeling “puffy” from water weight can lead me to bad self-image and thoughts (“ugh this waistband is cutting into my stomach, I feel fat”). It’s helped me to realize this feeling is not something really reflected to others—my friends don’t notice 5 lbs of water weight on me even though it might preoccupy my mind. I think it might be worth talking to someone about the mental aspect of this issue as a different approach than replicating high altitude conditions.
posted by sallybrown at 1:27 PM on April 9 [1 favorite]

Thanks everyone. I'll just add/clarify a few things in case anyone has the same question in the future is interested in details.

-A few people mentioned drinking water. I was drinking the same type and amount of water as always and didn't notice anything different in terms of thirst, etc. But it's interesting to think about how the body processes water differently in different environments.

-Similarly with exercise - although I was doing about the same amount of walking, I was trying very hard to not exert myself because I have some potential risk factors for altitude sickness. I didn't really consider how movement may nonetheless have affected my body differently at a different altitude.

-A few mentioned macros/keto etc. I always eat high carb (basically similar to 80/10/10 or HCLF without being vegan or even vegetarian) and I was eating even higher carb during this trip. In general I do very badly in every possible with high protein and/or high fat diets, so I won't be trying that again! But I know that works well for some.

-I completely forgot about this, but I have lived in the desert before (just never been to the high desert) and yes sallybrown, my hair improves so much in dry climates! I agree about the uncomfortableness of it. For me, those few extra lbs - even if it's just water - really affect my bad knees, which is a major reason to try to keep it off. Also I loved being able to cross my legs more comfortably and just move around as if my body was mine and not wrapped in a suit of puff. And other people do notice it on me.

It's good to know this happens to others as well, and also I suppose it's good to know it's temporary, so I won't always be vaguely tempted to move to Albuquerque.

I suppose my real question should be, what are healthy ways to reduce and prevent water retention, so I'll look into that more.
posted by DestinationUnknown at 8:55 AM on April 11 [1 favorite]

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