Does being fat-adapted give you an edge in survival situations? page

[golangrok]

Is there any research on this?
What I'm specifically thinking of is hypothermia...if you were fat-adapted, would your body start burning body fat to maintain temperature?

[patrickh]

I don't think being fat-adapted, in terms of substrate usage, would help very much. I think being cold adapted would be far more beneficial in terms of maintaining core temperatures in the cold. I don't have any numbers to back this up. However, taking regular cold showers (even in the winter) and working out in the heat has made me much less bothered by either temperature extreme. I now prefer to wear shorts and a t-shirt even into the late fall.

[Lewis]

Is there any research on this?
What I'm specifically thinking of is hypothermia...if you were fat-adapted, would your body start burning body fat to maintain temperature?

Survival situation? How long are you without food? I guess you'd adapt anyway in the absence of any other fuel source.

But there'd be some quite complex things going on. You could ask Jack Kruse. He's deeply interested in the cold and seems quite ready to take questions from people:

Ask Jack

[sbhikes]

Is there any research on this?
What I'm specifically thinking of is hypothermia...if you were fat-adapted, would your body start burning body fat to maintain temperature?

I asked a similar question in a backpacking forum, not so much about hypothermia, but I was curious if being adapted to a ketogenic diet could potentially make you better able to stay warm on a cold night and reduce the weight of gear you need to carry. There was a huge discussion, but I'm not sure if anybody really knows the answer. I suppose there's one way to find out.

As for hypothermia, once you reach a state of true hypothermia, you're kind of beyond what your body is capable of withstanding by default. It's a serious condition. Lots of things will help you survive it, your fitness level, your basic health, your knowledge of what to do and possibly your metabolic flexibility. Basically, if you can burn your body fat to maintain temperature, you aren't hypothermic. And if you are hypothermic, you can't just sit there and wait. You have to act.

[Lewis]

Strangely, it seems the mind can play a role, too. There are supposedly cases of people who died in situations in which they imagined themselves to be cold but that weren't actually that cold. Likewise, people have survived situations that are commonly thought to be "too cold". I suppose the baby in the cold-drawer morgue in South America that was thought to be dead but wasn't, who was in the news recently, didn't hold an opinion either way.

But belief and attitude have a wider significance, too. I'm reminded of the Japanese man in the raft, who walked off it after a lengthy exposure, because of his mental attitude. People have, however, been prostrate after being found after just a day or two "lost at sea".

Dr Kamler has some on this:

Amazon.com: Surviving the Extremes: What Happens to the Body and Mind at the Limits of Human Endurance (9780143034513): Kenneth Kamler: Books


According to Dr. Kruse, a ketogenic diet and high levels of omega 3 enable one to withstand the cold better. This seems to be partly down at the level of what the cell-membranes are doing. But while there is interest I don't think there's a huge amount of research.

COLD THERMOGENESIS 5 | Jack Kruse

[AmyMac703]

Even in the earliest stages of hypothermia, mental function can be affected, so situations where people's mindset seems to affect their tolerance of cold could be the result of an altered mindset (because of the cold) to begin with. It seems like a pretty complex question.

As for general cold tolerance, I think that being in overall good physical condition and adapted to the cold (living somewhere where it gets cold regularly) have way more of an affect than diet. The problem with trying to do a study or even use anecdotal experience from people who do winter-based outdoor activities is that you can't isolate one factor -- most people who go paleo experience some general physical improvement as a result (be it fat loss, improved cardiovascular fitness, or something else), so you can't really know if it was the diet itself or the physiological effects of the diet that causes changes in your cold tolerance.

[Forgotmylastusername]

Most peoples cold tolerance goes right down on very low carb as it tends to lower thyroid hormones. But if you're in a state of starvation that's probably going to happen anyway and make no difference, but you'll probably be better off if you have some glucose stores to use up first though. Overweight people would definitely have the edge in survival situations.

[sbhikes]

Even in the earliest stages of hypothermia, mental function can be affected, so situations where people's mindset seems to affect their tolerance of cold could be the result of an altered mindset (because of the cold) to begin with. It seems like a pretty complex question.

As for general cold tolerance, I think that being in overall good physical condition and adapted to the cold (living somewhere where it gets cold regularly) have way more of an affect than diet. The problem with trying to do a study or even use anecdotal experience from people who do winter-based outdoor activities is that you can't isolate one factor -- most people who go paleo experience some general physical improvement as a result (be it fat loss, improved cardiovascular fitness, or something else), so you can't really know if it was the diet itself or the physiological effects of the diet that causes changes in your cold tolerance.

In my case, I was an active backpacker living in Southern California, so not much in the way of experience in winter-based outdoor activities. But I had plenty of backpacking experience since I hike every weekend and usually take about 4 section hikes of about 4 days each on the PCT ever year, and maybe a few more backpack trips elsewhere. I hiked the complete PCT in 2008 and 2009.

Shortly after I turned the corner on becoming adapted to a low carb diet, I went on a backpack trip at about 5000 feet elevation or so. I was surprised to see the place was a winter wonderland. I had never camped ON snow before, although I have walked over it before. We had to camp on the snow. All I had under me was a z-rest pad, basically a 3/8" closed cell foam pad. Fortunately I had two down quilts with me. Quilts are open to the ground so I slept directly on the foam pad. Sleeping on the snow like that was VERY cold. I had to find positions that put the least amount of my body in contact with the floor. But I managed. It wasn't too bad. I have nothing to compare because I have never had to do that, but it made me wonder that perhaps being able to burn fat for energy helped me sleep that night.

The trip was awesome because I was able to hike with more energy than I've ever had before while eating far less often. I never needed to snack. I postholed and broke trail in the snow without tiring. It was awesome. I definitely felt amazing on that trip, unlike anything I had experienced in my long resume before. A feeling of incredible health, stamina and ability to just roll with it.

Last spring I was out backpacking with some friends and it started to rain and became very cold. My poncho disintegrated in the overgrown chaparral scrub. I was soaking wet. I tried to hike as fast as I could to stay warm but eventually I had to admit that I would need to put on some of the clothing I was saving to stay warm in bed. When I reached the most-likely spot for us to camp, I waited under a tree for my friends. There were a couple of lame-ass boyscouts trying to start a fire but they couldn't do it. I wasted time trying to help them and finally just gave up and shivered there waiting for my friends. They took a long time to arrive. Finally one of them showed up and he was really worried about me and started barking orders at me. I kind of snapped out of it and went to work. When we both realized that neither of us had any stakes for our shelters, I showed him how to make deadmen to set up his shelter. My hands were numb by this time and I was shaking uncontrollably. Long story short, we both got our shelters up and got inside. It took an hour to stop shivering. In the end, I slept completely naked but I was warm all night long, and in the morning I had to hike out to the car wearing cold, wet clothing. But I was fine.

I have no idea if being fat-adapted helped me in that situation or not, but I'd like to think that my improved health overall since adopting a diet that clears up my insulin resistance, gives me more energy, allows me to use body fat for energy and takes away all the inflammation was nothing but helpful.

All that crap about lower thyroid is BS and should be ignored. It's a misunderstanding of what actually happens.

[golangrok]

This is turning out to be a fascinating topic.

[Forgotmylastusername]

All that crap about lower thyroid is BS and should be ignored. It's a misunderstanding of what actually happens.

No, it's reality. Ketosis mimicks starvation and can lower t3, how that effects people can vary. Ask someone like Chris kresser who has his own practice what very low carb diets can do to many of his patients. It doesn't 'destroy' or permanently harm the thyroid as it can be reversed with dietary carbohydrate.

“And I definitely see this, Chris, in my practice, and this is purely anecdotal, but I often get people who come to me who have been on a low-carb Paleo Diet, not for any particular reason, just because that was their understanding of the Paleo Diet, you know, as a low-carb approach. And then they’re suffering from the classic hypothyroid symptoms: Their hair is falling out, and their hands and feet are cold, outer third of the eyebrows thinning, you know, low metabolic symptoms. And then they start eating some more starch and starchy tubers and fruit and increase their carbohydrate intake; and in almost all cases, their symptoms improve significantly.“

Dietary-induced alterations in thyroid hormone metabolism during overnutrition.

"It is apparent from these studies that the caloric content as well as the composition of the diet, specifically, the carbohydrate content, can be important factors in regulating the peripheral metabolism of thyroid hormones."

Isocaloric carbohydrate deprivation in... [Clin Endocrinol (Oxf). 2001] - PubMed - NCBI
"We measured thyroid hormone levels, resting energy expenditure (by indirect calorimetry) and urinary nitrogen excretion in six healthy males after 11 days of three isocaloric diets containing 15% of energy equivalents as protein and 85%, 44% and 2% as carbohydrates. In contrast to the high and intermediate carbohydrate diets, carbohydrate deprivation decreased plasma T3 values (1.78 +/- 0.09 and 1.71 +/- 0.07 vs. 1.33 +/- 0.05 nmol/l, respectively, P < 0.01)"

Effects of slimming and composition of diets ... [Am J Clin Nutr. 1982] - PubMed - NCBI
." Another group of nine subjects were studied at their spontaneous caloric and proteic levels, comparing a diet containing only protein and carbohydrate with a diet containing only protein and fat. During the low carbohydrate diet rT3 increased and T3 decreased but they remained unchanged during the carbohydrate-rich diet"