Background
A central topic of peatarianism is to focus on increasing the metabolic rate using various methods. It is hypothesized that this leads to better health and longevity. Ray Peat also says that having a TSH at or below 0.4 would be optimal.My recommendation is to eat to increase the metabolic rate (usually temperature and heart rate), rather than any particular foods. - Ray Peat (e-mail response)
I think it's best to keep the TSH around 0.4 - Ray Peat (e-mail response)
I think it's good to have TSH below 0.4, and that probably contributes to loss of hair. - Ray Peat (e-mail response)
What does the evidence say?
- In a prospective study in men with around 40 years of follow-up, a
higher basal metabolic rate was independently associated with a higher
mortality compared to average metabolic rates. Low metabolic rates were
not significantly associated with higher mortality (Figure: Mortality
plotted according to quartiles of metabolic rate).
http://www.ncbi.nlm.nih.gov/pubmed/18693224
- In the same study, a higher temperature was associated with
increased mortality compared to people with a lower temperature over
25-years of follow-up (Figure: X-axis: Survival time (yrs), Y-axis:
Cumulative survival; plotted for higher or lower body temperature).
http://www.ncbi.nlm.nih.gov/pubmed/12161648
- Mice that have been genetically engineered to have a 0.3 to 0.5°C lower body temperature have an increased life span compared to normal mice despite having the same caloric intake. http://www.ncbi.nlm.nih.gov/pubmed/17082459
- In a prospective study in male and females with average 11 years of follow-up, a higher 24 hour energy expenditure was associated with higher mortality from diseases. http://www.ncbi.nlm.nih.gov/pubmed/21450984
- In a 16-year follow-up study, an elevated resting heart rate in
men without cardiovascular disease is associated with an increased
all-cause mortality, even when adjusting for cardiovascular risk
factors. A lower resting heart rate wasnt associated with higher
mortality (Figure: All-cause mortality according to groups of resting
heart rate).
http://www.ncbi.nlm.nih.gov/pubmed/23595657
- In a prospective study of 52.674 participants with median 8.8 years follow-up, a TSH under 0.45 mIU/L is associated with increased all-cause mortality, cardiovascular mortality and atrial fibrillation compared to a TSH between 0.45 to 4.49 mIU/L http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3872478/
- In two cross-sectional studies of long lived individuals, longevity was associated with lower fT3 and fT4 and higher TSH values http://www.ncbi.nlm.nih.gov/pubmed/20739380 http://www.ncbi.nlm.nih.gov/pubmed/20843963
- A genetic polymorphism that leads to higher TSH is associated with longevity http://www.ncbi.nlm.nih.gov/pubmed/19837933
- In a prospective study of 85-year olds with 4-years of follow-up, a TSH over 4.8mIU/L is associated with significantly lower mortality compared to subjects with average or suppressed TSH levels. Low serum T4 combined with high TSH was also associated with lower mortality. http://www.ncbi.nlm.nih.gov/pubmed/16642639
- Centenarians had a higher TSH compared to younger controls. No differences in fT4 values were found. http://www.ncbi.nlm.nih.gov/pubmed/19158193
- Italians "oldest-old (90-107 years) had a higher TSH, lower fT3/fT4 ratio and lower serum zinc and selenium than adult or elderly control subjects. http://www.ncbi.nlm.nih.gov/pubmed/10852460
Conclusions
Having a higher metabolic rate, temperature or pulse or a TSH below 0.45 is associated with increased all-cause mortality. The underlying cause of these association is unclear. High metabolism or suppressed TSH can be a consequence of stress and elevated stress hormones, but also of high thyroid hormone action. The biomarker studies suggest that a slightly suppressed thyroid function may be protective, especially in elderly people. This effect may or may not be explained by the nutrient-sparing effects of hypothyroidism in populations prone to malnutrition.Given the lack of trials that show that increasing temperature and pulse by dietary measures or suppressing TSH with thyroid medication actually improves health, any broad recommendation to do should be stated in a careful manner. People need to be aware that they conduct a personal experiment when pursuing such hypotheses, especially when doing so for long periods of time.
All in all, it seems adequate to say that there is a narrow range between both hypo- and hypermetabolism that is associated with health in the long term.
It's better to burn out than fade away. .
ReplyDeleteThanks, Bukowski, for all your work on this and other pieces. I suspected as much but you've done all the hard work for me! I'll continue to follow your blog for sure.
ReplyDeleteI'm really happy to find this. I've been taking thyroid and keeping my pulse and temperature high but not feeling any better! In fact, I'm probably feeling a bit worse --especially with temps at 99 and up, and feel like I've aged more rapidly than in previous years.
ReplyDeleteI think the more the metabolic rate increases, the more fine tuned the diet, mineral balances, etc. have to be. Most people who take thyroid because Peat said so probably don't have the full, broad understanding needed to accommodate the higher metabolic rate, and are just aiming for general increases in certain parameters, like temp, pulse etc., not understanding that these variables can be elevated just as easily by a stress state.
ReplyDeleteWhy follow such parameters at all if they totally leave you in limbo whether you are in a stressed or relaxed state? They seem to add more confusion than help.
DeleteAll this study shows is that fatasses with no concern of what they put in their mouths have higher mortality then the health-conscious general public. No one in this study was eating pro-metabolically. Fat-asses have higher pulse because their hearts work harder, not because they have high functioning metabolisms.
ReplyDeleteYou bring a good point
DeleteI appreciate hour work but you're completely neglecting cortisol, which can often mimic thyroid with respect to heart rate and temperature, as well as TSH.
ReplyDeleteRegarding cortisol & longevity: http://www.empiri.ca/2014/02/red-light-green-light-responses-to.html
DeleteAt first glance, Regarding the first study body temp, cortisol also raises body temperature, particularly in the morning or after fasting. Temperature is typically considered with heart rate.
ReplyDeleteRegarding the second study of mice, Peat agrees uncoupled mice live longer. They produce more CO2. Adrenaline increases core body temperature, while the extremities are cold.
Regarding the third study of Pima Indians, the largest cause of death appeared to be alcoholism, alcohol toxicity and liver damage, then confusingly listed quite a few fractures as cause of death, possibly from car accidents.
That's what I've read so far. It's a limited subset of studies, and some studies have limited utility. I don't see enough observation to state the conclusions of the blog entry yet
High metabolism + low nutrients is going to kill you faster than low metabolism + low nutrients
ReplyDelete