Body Temperature in Decline

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There is really no question that average human body temperature is in decline. Even the New York Times recently wrote an article on the subject, being, as clueless as ever, about the real significance of such a thing.

For well over a year now, there has been much focus on the basal body temperature at 180DegreeHealth. This came, in part, as a result of reading all of the books of Broda Barnes, Stephen Langer’s book on hypothyroidism, and perhaps my favorite book on the far-reaching impact of having a low body temperature – Type 2 Hypothyroidism: The Epidemic, by Mark Starr.

I find much of my beliefs about the all-encompassing importance of the body temperature to be reinforced by the current book I’m reading – Ancel Keys 2-volume piece on calorie restriction called The Biology of Human Starvation. For starters, the huge drop in white blood cell count that follows the body temperature down during starvation is particularly interesting, as another avenue I’ve travelled down in the last year is one in which pathogenic viruses and bacteria are the root cause of most health problems – both acute and chronic.

Is it any wonder then that Henry Bieler has this to say about those with a body temperature that is “scarcely ever below 98.8 degrees F?”

“… leucopenia, or abnormal white cell count on the low side, is never noted… The immunity against bacterial invasion is spectacular. The typical adrenal type hardly ever becomes infected, even with venereal diseases…”

Yet, Ancel Keys found the men in his starvation study, as the metabolism slowed and body temperature fell in accordance, had white blood cell counts drop dramatically – by 34.9% in just 24 weeks. To see all the important roles of the many types of white blood cells in protecting us from a wide array of diseases, take a peek through Wikipedia’s page on white blood cells.

This should come as no surprise really. We all can observe that in areas of famine and malnutrition infectious disease runs rampant as body temperatures fall in response to calorie and nutrient deficiency. I think back to Layla and her family, who were in excellent health living in squalor in Somalia until they became malnourished – at which point they all fell ill to dysentery and malaria for the first time. I also cannot forget the studies of Robert McCarrison on nutritional deficiency disease in which his animal subjects on nutrient-deficient diets all perished in the presence of a pathogenic bacteria while his well-fed subjects not only survived the pathogen but remained entirely symptom-free even living in ass-to-mouth confinement.

It came as no surprise to discover that the animal subjects who perished were later autopsied and found to have atrophied thyroid glands – no matter what the nutrient deficiency was. It’s safe to say that under circumstances of ANY nutritional deficiency, the body has the same hypometabolic response.

This is just one tiny fragment of the overall importance of the body temperature in protecting us from disease. In terms of just basic fundamentals, body temperature controls the activity of our cellular mitochondria. Cellular mitochondria are the energy source of all life processes. Blood circulation, synthesis of steroid hormones, enzyme activity, fat-burning, bowel transit time, fertility and libido, and more are just a small fragment of the body systems that are all degraded when body temperature/basal metabolism/mitochondrial activity is reduced.

There is no part of the body, no organ, no muscle – not a single cell, that isn’t influenced by the basal metabolic rate. In fact, I challenge anyone to find a diseased state that cannot, in some shape, form, or fashion – be linked back to the basal metabolism somehow.

We even have mitochondrial DNA that helps to determine the heredity of the future generation we bring into the world. Seeing Mark Starr link mitochondrial DNA to the facets of Weston A. Price’s “intercepted heredity,” such as mouth-breathing, pelvic narrowing, susceptibility to infection including dental decay, and malformation of the jaw and dentition was one of the most revealing pieces of information I’ve come across.

It gave specificity to why people all over the world lost their former great health and superb physical formation and function upon the displacement of traditional foods with modern, refined foods – a low basal metabolism.

It also gave great insight into the association between parent age and offspring health problems – as the older we get, the lower our body temperatures tend to go, and the older the parents, the greater the chances for health problems amongst the children.

The most important remaining questions are:

What, specifically, is leading to this drop in body temperature?


How can we fix it?

The answer to those questions, as we all know by now, is extremely complex, individually variable, and probably can’t be answered with a one-size-fits-all set of dietary and lifestyle recommendations.

The most likely culprits are (and yes they work in combination):

Too much fructose (perhaps inducing leptin resistance which drops body temperature)

Too much dietary omega 6 (which creates an over-inflammatory condition in the body, which may also be causal in the development of leptin resistance, and can certainly cause excess cortisol to be released and trigger the same “metabolic syndrome” pattern)

Nutrient deficiency (Remember that any nutrient deficiency causes the thyroid gland to atrophy in ALL of McCarrison’s laboratory animals – from pigeons to monkeys)

Infectious organisms (although, like I mentioned above, I think the low body temperature is the egg that comes before the chicken – a low body temperature allows infectious organisms to thrive for several reasons, being hypometabolic is the opposite of having a germ-fighting fever)

Environmental contaminants/toxins (I also believe that most of these accumulate, except in rare cases of severe exposure, due to reduced neutralization, detoxification, and excretion capabilities of a body with a low basal metabolism)

And as most of you already know by now, I feel that the best method of overcoming these imbalances is to eat a very nutritious, high-calorie, and very low omega 6 and fructose diet for at least a few months while resting and getting plenty of sleep – and also keeping caffeine, drug, and alcohol consumption at a minimum. I am also open to supplementing with large doses of vitamins and minerals that are confirmed to be low – such as vitamin D or iodine to overcome drastic deficiencies. Of all the healing diet and lifestyle regimens ever composed, it appears that the milk diet as was commonly used in the early 20th century has the most potential – as authors of the day reported dramatic health improvements as well as several changes directly attributable to an increase in metabolism – such as increased resting pulse, increased body temperature, increased total blood volume, and so on.

If none of the above “do the trick,” then desiccated thyroid hormone can and probably should be used to bring the basal metabolism back up to optimal levels. It is difficult to really feel and function your best if your body temperature is low, which is the first thing that nearly everyone should address when attempting to tackle any health problem. One way or another, it is probably better to have a normal basal temperature than a low basal temperature no matter how you go about bringing it up to speed.

The supposedly optimal basal temperature and how to test it properly will be addressed in a short and simple post tomorrow.


  1. Excellent, best summary of the ideals here yet.

    I have posted this before, but seems that +0.1F per month is the norm so far for me. Hopefully at one year – Oct 2010, I will be at ~98.0 basal up from the mid 96F at beginning.

  2. Hmmm. You mention infections and environmental toxins as possible causes for a hypometabolic state.

    Iodine is strongly antibacterial and able to detox halides and some heavy metals. So I guess iodine really might be something to look further into for many people. Well, we'll see what it does for me.

  3. What about sleep deprivation, overexercise and other stresses?

  4. Definitely Markus. Although I think the healthiest of people seem to be able to get away with that kind of thing, I find that dealing with a low metabolism by overexercising, cutting calories, and not addressing stress and sleep-deprivation make the root problem exponentially worse. Not always causal, but certainly counterproductive.

  5. Did they actually measure basal temps in Ancel Keys study? If so, how did those change during the starvation and refeeding phases?

  6. Good post, Matt.

    I'm glad to see you mention parental age. I waited until I was almost 40 to start having children, and the demands of pregnancy were what pushed me over the edge into illness. Plus one (formerly) autistic kid. People would warn me about not being able to get pregnant if I waited, but no one ever said a peep about what it could do to my health and the health of my kiddos.

    And lord, it's exhausting having kids! Not a job for the middle-aged.

    I'm always urging the youngins to procreate while they're young and strong!

  7. Temps were measured in Keys study along with just about everything you can think of. Plus, the results of many other starvation studies or famine reports are also looked into closely. Temps went down during starvation, and up during refeeding. Shocking I know.

  8. Yeah, was just curious about how the temperature curve followed the body weight/body fat curve you posted earlier.

    I gotta get me that book.

  9. My body temperature has been a little low ever since I was a kid. I remember my mom telling me hers had always been that way, too, so I thought it was genetic. Now in the past couple years it's started to dawn on me it could be a sign of something deeper.

    You know that's another reason I want to stay on the milk diet for a full four weeks, because I want to reliably track my temps (since temps flucuate with mentstrual cycles). So far my temps are quite high, but it's the middle of my cycle so I'll have to wait and see if it lasts.

    Nell – You bring up a really great point. My husband and I have had similar diets since we met ten years ago, so I always wondered what did me in when his health is basically fine. Although I think dieting, stress, and over-exercising had a hugely negative impact on me, having two pregnancies relatively close together (and being food/exercise obsessed during and after my second) really wrecked my health. It was a lethal combination for me. And I'm young. I don't even want to know what pregnancy would have done to me if I were older.

  10. I'm no Ancel Keys, but I'll just throw out my own personal case as an example.

    Number of hours of sick leave last summer when it wasn't even flu season, but I was following an extreme diet with too much exercise and not enough rest: 48

    Number of hours of sick leave this winter during flu season: 4. (And these were for preventative doctor visits for me and my kid.)

    I've always had a low body temperature. Even as a kid, I really needed to feel seriously feverish to register over 98.6. I was always the kid who got every bug, too.

    Hey, speaking of Ancel Keys, the U of MN just release a study linking soda consumption to pancreatic cancer.

  11. Elizabeth: My temps go up mid-cycle as well, though, I've found adequate rest and keeping away from sugar and white flour will get me close to normal. I can usually tell if my temps are truly "up" by how my digestion is and weather my hands feel cold when I'm just sitting at my desk.

    "And lord, it's exhausting having kids! Not a job for the middle-aged."

    Word. This is clearly a design flaw in the species.

  12. The only thing that I am trying to reconcile is this crazy calorie restriction and longer life span thing, which is well documented. These two approaches are at opposite ends of the spectrum. BUT Roy Walford, the CRON guru, died at 79 y.o. from ALS. Subsequent studies with rats show that calories restriction makes ALS WORSE! Keep in mind that the, uh, "husky" Marlon Brando outlived Roy by living to be 80. I'm still confused but I am rooting for Matt, LOL!

  13. Well it's going to take a long time on HED to cancel out years of calorie restriction for me. If you are eating a typical SAD diet, maybe eating less of it is better for your longevity than eating more. IF your main source of fat is veggie oil than it's better to eat less fat than more toxic oil. Just think how long Marlon Brando would have lived had he been a champion eater of nourishing foods. He coulda been a contender, I think.

  14. Matt, you were criticized recently on other blogs for staking your claim on 98.6 (or maybe now 98.8) as the best body temperature, which may be fair as I would expect some variation between individuals.

    But, as you pointed out, the overall trend is down, and that is not a good ting. 98.6 is(was) considered the ideal temperature because it was an average, most people were 98.4 to 98.8. But now, the NY Times claims the average is going down! It seems to me these haters are looking for something to hate on, not actually understanding what implications a low body temperature has. Not good.


  15. Scott – I tend to agree. Maybe there is no exact "ideal" temperature for everyone, but regarless I think it's useful to track temps to see if there is a downward or upward trend. That would give great insight into what going on in your body – not just what the temperature is, but whether it's trending up or down.

  16. This post has me concerned now that my white blood cell count has gone down quite a bit over the past 6 months and is under the recommended level. I would have expected HED to raise it if anything??

  17. My basal temps improved quickly when I began HED from the low 96s to 97.7 within several months, but it's plateaued since then and it still 97.7 today. I can't break 98 it seems, let alone approach the ideal temps. And it really bums me that I can't figure out why.

    Perhaps I do need desiccated thyroid but I'm hold off on that, as it feels like "giving up" on actually healing my metabolism. I figure I'm deficient on something but I can't figure out what. O-6 and fructose consumption have been minimal for months now and I finally kicked caffeine two months ago now. Meh.

  18. Will-

    In a laboratory, calorie restriction = longevity. But remember that this is a controlled lab that is sterilized. I don't see this translating to the real world. In fact, cutting calories has been noted by Keys as leading to graying hair – something that was reported in times of famine.
    Plus, in areas where there are low calorie intakes such as parts of Africa, the death toll from infectious disease is astronomical – and would improve dramatically if better food supplies were available.

    I was definitely thinking about you with the low white blood cell count. It is very odd that it has dropped on HED. If you ever solve that puzzle I'd love to know what did it.

    Body temperature is very key. Those who point to averages are probably average, but that's not really the goal here. There's a reason why older people get more health problems, aches and pains, and degenerative disease – body temperature tends to fall with age. The key is to figure out how to stop that progression. Broda Barnes did it. Mark Starr is doing it. And we are exploring dietary and lifestyle strategies to prevent and reverse the same temperature decline.

    I haven't ever hit a temp. at 98 or above either. If I do start to approach the high end of Broda Barnes's "healthy range" I'll let you know how I got there. But I'm feeling plenty good at 97.7 and I know you're doing well at that temp as well. It's a big jump from the 96's.

  19. You mention fructose is bad for body temp and metabolism, but what about regular sugar, honey, or maple syrup. Again, going back to my peeps in Italy, they eat tons of sugary treats every day, don't seem to have these problems.
    My son is 34 months and kind of large, he always has been. He is 39 inches and 41 pounds…should I be concerned? My husband is freaking out about this and is starting to restrict his food and I'm not sure this is the best thing. My son is very healthy, no antibiotics ever, had a slight fever for about a day more than a year ago, but that is about it. So, I'm trying to say that if he is so healthy in this way, is his metabolism still low since he is a few pounds overweight?
    He eats the same food we do, no processed, never had any fast food, plenty of whole grains, veggies, fats, and protein. He does, however have fruit everyday and a cookie or chocolate about everyday. Cookies only with real sugar and butter. Should I cut those out or is it ok for a healthy little one?

  20. Since HED my morning temps are just below 98 and afternoon temps just above. That's more than a 2 degree improvement. My gyno told me that low body temps are NOT an indicator of hypothyroidism and truthfully my TSH is "normal". But I bet Broda Barnes would have written me a script for dessicated thyroid based on my symptoms.

    Personally, I don't believe my gyno about the temps. I know my metabolism is screwed. Question is can I fix it? My weight seems to have stablized since my temps have come up and my appetite seems to have decreased. Yes, I'm frustrated that I can't seem to lose weight but I'm feeling better and sleep well so maybe this is as good as it will get? Wait (and weight) and see.

  21. My Temp was 98F this morning, (just ovulated so up 0.3°C from yesterday) but i do oral not under arm temps ;)

  22. Vida-
    Don't worry about your kiddo. I have 2 boys, a 3 yr old who is 40lbs & a 5 yr old who is 60lbs and they are healthy (just off the charts in weight & height)and eat like your boy does. They are excellent at self-regulation. Don't restrict his food just make sure what he has available is what you want him to eat. I would love to remove sugar from their diets but that is not going to happen right now. Instead we talk about the effects of sugar why those are treats and not snacks. I hope this helps.


  23. Since oral & axillary temps can differ by as much as one degree, which temp are most people talking about?

  24. I think Matt and the others are talking axillary, that's why i specified oral ;)

  25. Will, the calorie restriction data is not inconsistent, if you actually read the studies.

    What they have found is that rat pups put on a restricted diet from birth grow up stunted, and just like small dogs live longer than big dogs, the runts live longer than their full sized bretheren by some measure.

    But that does not mean that adult intervention of calorie restriction is beneficial. Quite the opposite. Rats put on a calorie restricted diet as adults had the shortest lifespans of all the tested groups.

  26. Any benefits of calorie restriction (hugely qualified by feeling cold, no sex drive, irritability, fuzzy thinking (once adrenaline runs out) seem likely to be a result of restricting pro-aging substances. Ray Peat has written well on this. Restricting PUFAs, tryptophan, cysteine, heavy metals (iron)etc. will have the same benefits without destroying the metabolism.

    do a search for "calorie OR caloric restriction" on for his references

  27. Another and far better point Cusick. Thanks. One that is totally congruent with personal experience I might add.

  28. In reading the comments thread on a recent New York Times article about vitamin D I came across a website,, that has an alternate theory on vitamin D. They believe that vitamin D is immunosuppressive and the improvements seen in people supplementing with vit D are due to decreased cytokine activity as a result of less bacteria (specifically L-form bacteria) being killed. They believe long term elevated levels of D are harmful. After reading through their stuff I have to say its a pretty good theory. Now I don't know what to think. But I was reminded of it by your comment in this post about the bacterial cause of chronic disease.

  29. Matt Stone wrote:
    "We even have mitochondrial DNA that helps to determine the heredity of the future generation we bring into the world. Seeing Mark Starr link mitochondrial DNA to the facets of Weston A. Price’s “intercepted heredity,” such as mouth-breathing, pelvic narrowing, susceptibility to infection including dental decay, and malformation of the jaw and dentition was one of the most revealing pieces of information I’ve come across. "

    Wow, Matt, this is stunning!!!! It all begins to make perfect sense.

    On the topic of the "pinched noses", do you happen to know anything about Buteyko breathing? I am struggling with chronic hyperventilation syndrome (over-breathing) caused by too much mouth breathing (and I have a pinched nose too). I am certain there is some important connection between chronic hyperventilation syndrome (CHS) and a low metabolism (since I suffer from both). I'd love to hear your take on all of this.

    Dr Buteyko (who discovered the connection between chronic disease and low oxygenation of the cells, ie CHS) himself writes this:
    "Deficiency of CO2 caused by deep-type breathing[…]brings about alterations in metabolic processes."

    Perhaps it is the excess cortisol that leads to over-breathing? Infections?

  30. Haven't reviewed Buteyko yet but I do have the eBook and will review it before the end of the year.

  31. Love it! What eBook do you have?

  32. Can't even remember. I have it tucked away in an old e-mail somewhere.

  33. Hi Matt, I found your site recently and am very interested in your ideas. RRARF intrigues me, but something that I've been wondering is: after body temperature raises through a process like RRARF, wouldn't it fall again after the weight comes off?

    - Lily

  34. Hi Lily,

    Not everyone gains weight through RRARF. Some actually lose weight, especially if you are coming off a typical SAD diet.

    But the idea is that body temperature gains are maintained, and any weight you do lose should be done while monitoring body temperature to make sure it is not falling.

  35. Hi Matt
    I first read about low body temperature and immunity problems some years ago in the 'Immune Restoration Handbook' by Mark Konlee. You can google him and find the site. He had gathered much research on what causes immune dysfunction in immune related conditions such as HIV,Chronic fatigue and Candida. He suggests several ways to raise body temperature, including kelp and cayenne capsules, plus the whole lemon/olive oil drink that he uses as part of his nutrition program.
    All the best, Victoria

  36. Who has written this article? I’m using it for an assignment so I’ll have to know.

  37. Nevermind. I found out… :-) Matt Stone, I suppose?



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