Is Ray Wrong About Raised Metabolism?

[ecstatichamster]

http://biomedgerontology.oxfordjournals.org/content/63/7/698.full.pdf+html

It is remarkable that in both animals and humans caloric restriction causes a reduction of BMR that is independent of changes in body composition (16,19,20). On the contrary, conditions characterized by pro-inflammatory status and immunological activation, which are strong predictors of mortality, are associated with an increased BMR attributable, at least in part, to bioenergetic dysregulation (21,22). Taken as a whole, these observations suggest that higher BMR may be associated with higher mortality.

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The risk of death increased significantly as a squared function of BMR, expressed either as kcal/m2 /h or kcal/ kg/h, and independent of age, date of visit, race, weight, and BMI (Table 3, Model 1).

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Independent of age, participants with BMR in the range 31.0–33.0 kcal/m2 /h had the lowest mortality, whereas above the threshold of 33.0 kcal/m2 /h the mortality risk increased linearly, and the participants with BMR .36.0 kcal/m2 /h experienced excess mortality compared to the average mortality of the population. A slight and almost negligible increase of mortality was observed for values ,31.0 kcal/m2 /h (Table below Figure 2).

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On the basis of data collected longitudinally from healthy community-dwelling persons who participated in the BLSA, we found that BMR declined nonlinearly with age. Independent of age, participants who died during the follow-up period tended to have a higher BMR compared to those who survived. Accordingly, higher BMR was associated with increased risk of mortality independent of age, weight, BMI, smoking status, total physical activity, muscle mass and strength, white blood cell count, diabetes, blood pressure, and calendar date. The relationship between BMR and mortality was curvilinear with minimum mortality between 31.0 and 33.0 kcal/m2 /h and with progressively rising mortality above 33.0 kcal/m2 /h. These findings are the first evidence based on longitudinal data showing that a blunted capacity to reduce BMR with age is a significant risk factor for mortality in the general population

 

[hmac]

I don't know if he's wrong or not but BMR is also elevated by stress so it depends on what's causing the elevated metabolic rate.

 

[Nicholas]

I don't know if he's wrong or not but BMR is also elevated by stress so it depends on what's causing the elevated metabolic rate.

the idea of Peat being "slightly hyperthyroid" is not elevated metabolism....it is elevated stress. hypothyroidism and hyperthyroidism are the same when it comes to being a malfunctioning metabolism.

 

[ecstatichamster]

i'm wondering if they measured wrong. They derived BMR and compared it using kilocalories per square meter of body per hour.

Participants were housed on a ward and underwent indirect calorimetry in fasting, resting state for the two following mornings between 7:00 and 9:00 AM in a temper- ature-controlled room. BMR was estimated from basal O2 consumption and CO2 production measured by the open- circuit method described by Shock and Yiengst (25) and Tzankoff and Norris (26). Samples of expired air were collected for 6–8 minutes during three collection periods. Until 1965, O2 and CO2 were analyzed by using a Haldane apparatus, and after that time by paramagnetic method for O2 (Paramagnetic O2 analyzer model G-2; Beckman Instruments, Fullerton, CA) and by infrared absorption (gas analyzer Model LB-1, Beckman Instruments) for CO2. After the two analytical systems were shown to be equivalent, all subsequent analyses were done by the more modern method. Both instruments were calibrated daily with standardized gas mixtures obtained commercially in standard pressure tanks and checked by the Haldane method. BMR was calculated from respiratory data using Lusk’s tables (27) and finally expressed as kcal/m2/h, based on DuBois’s equation to estimate the body surface area.

But is that accurate? I would measure temperature and heart rate as a proxy for metabolism. That's what I'm doing myself.

If I was going to use oxygen and carbon dioxide, BETTER HEALTH would correspond to less oxygen inhaled, and more CO2 exhaled. 4 - 6 liters per minute inhaled is better health than 14-20 liters per minute. CO2 has to be measured as a ratio.

According to Buteyko's work, MORE oxygen inhaled per minute means WORSE HEALTH. Did this study pick up men inhaling more oxygen per minute, and somehow derive that they had "higher" metabolic rates?

 

[ecstatichamster]

So here's how I'd summarize the problem here with this study:


The problem with this study, I think, is that they derived a metabolic rate by measuring oxygen inhaled and CO2 exhaled.

They decided this was a proxy for metabolic rate, coming up with kCal per square meter of body area per hour.

However, it’s been shown over and over, that the more air per minute someone breathes, the lower their state of health. Minute volume of air breathed is a proxy for health. Did this study select candidates with poor health and derive their BMRs as higher?

This study did not use the proper proxy for BMR. It selected for LESS healthy men by measuring BMR inappropriately.

 

[hmac]

the idea of Peat being "slightly hyperthyroid" is not elevated metabolism....it is elevated stress. hypothyroidism and hyperthyroidism are the same when it comes to being a malfunctioning metabolism.

Although there is that paper that Haidut posted "the effect of thyroid hormones on steroid metabolism" that shows that 'hyperthyroid' people had an increased clearance of estrogen and cortisol and an increased production of DHEA etc. Perhaps the definition of hyperthyroid is problematic.

 

[Philomath]

I've been thinking about how to check my metabolic rate ... Of course the capnometer is one of the ways to check the exhaled CO2 and thus metabolic rate. However, I remember Dr. Peat mentioning measuring the volume of liquids taken in and measuring the amount of fluids urinated out as a way to determine metabolic rate. Maybe the authors of the study should have used different tools to measure metabolic rate.

 

[Nicholas]

Although there is that paper that Haidut posted "the effect of thyroid hormones on steroid metabolism" that shows that 'hyperthyroid' people had an increased clearance of estrogen and cortisol and an increased production of DHEA etc. Perhaps the definition of hyperthyroid is problematic.

then there must be a terminology issue... or a confusion as to if increased clearance of estrogen and cortisol means you're in a better place. hyperthyroidism is associated with higher output of adrenaline, which raises cortisol. i wonder if having an overactive thyroid gland is physiologically very different from taking thyroid. Josh Rubin says that true hyperthyroidism is very rare. to use the term "slightly hyperthyroid" or viewing it as something that you can manipulate via thyroid hormone or through a "pro-thyroid" diet is probably not accurate. popular science defines hyperthyroidism as causing an elevated metabolism. so it sounds like metabolism is being defined or measured incorrectly, because having a higher output of adrenaline (even high levels of CO2 in the blood) is from a breakdown in the body, it's from a breakdown in metabolism. Google (correctly) defines metabolism as: the chemical processes that occur within a living organism in order to maintain life.

 

[tara]

If I was going to use oxygen and carbon dioxide, BETTER HEALTH would correspond to less oxygen inhaled, and more CO2 exhaled. 4 - 6 liters per minute inhaled is better health than 14-20 liters per minute. CO2 has to be measured as a ratio.

The problem with this study, I think, is that they derived a metabolic rate by measuring oxygen inhaled and CO2 exhaled.

My understanding was that measuring O2 consumed and CO2 produced is pretty much best practice for measuring metabolism. Heartrate, calorie consumption, waer evaporationg, etc may be rough proxies. I can't comment on the relationahsip to m2 of body surface divided by height.
IIUC, I don't think this is in conflict with Buteyko's or Bohr's theory. If increased CO2 levels, either from increased production or decreased losses, leads to more efficient oxygen delivery, it should be possible to get higher oxygen consumption with a lower breathing rate. Ie, with severe hyperventilation one would breath a lot of air in and out, but the exhaled air would contain a higher amount of oxygen because one had not mananged to deliver much of it to tissues. Whereas with reduced breathing, the oxygen level in the exhaled air would be significantly lower, because more of it had been used up.

 

[ecstatichamster]

My understanding was that measuring O2 consumed and CO2 produced is pretty much best practice for measuring metabolism. Heartrate, calorie consumption, waer evaporationg, etc may be rough proxies. I can't comment on the relationahsip to m2 of body surface divided by height.
IIUC, I don't think this is in conflict with Buteyko's or Bohr's theory. If increased CO2 levels, either from increased production or decreased losses, leads to more efficient oxygen delivery, it should be possible to get higher oxygen consumption with a lower breathing rate. Ie, with severe hyperventilation one would breath a lot of air in and out, but the exhaled air would contain a higher amount of oxygen because one had not mananged to deliver much of it to tissues. Whereas with reduced breathing, the oxygen level in the exhaled air would be significantly lower, because more of it had been used up.

I suppose percent of exhaled gas that is co2 would be a good proxy for metabolic efficiency. Not rate though.

Ratio of co2 exhaled and o2 inhaled is instead what I think they measured. If someone is sick they breathe in a lot more air. Might breathe out their co2 and be dying. But they would show in his study to have a higher metabolism.

 

[tara]

I suppose percent of exhaled gas that is co2 would be a good proxy for metabolic efficiency. Not rate though.

Why not rate?

The study methods say they measure:
"BMR, expressed as kcal/m2/h, was estimated from the basal O2 consumption and CO2 production measured by open-circuit method."

I didn't follow up the references to detailed descriptions of the Lusk tables, or the physical measurement method, but it looks to me as though they collected the exhaled air over a period, and used one of two methods to assess the amount of oxygen in the sample. So they had some numbers for not just breathing rate, but also the actual quantity of oxygen exhaled. Since they probably had a rough idea of the level of O2 inhaled, they could derive how much oxygen was consumed over a 6-8 minute period.

A low metabolism may tend to breath out too much of it's CO2, but a high (thyroid-based) metabolism should be able to produce CO2 at a faster rate, and therefore exhale it at a faster rate too, possibly while still breathing more slowly and retaining a higher level in blood?

Ratio of co2 exhaled and o2 inhaled is instead what I think they measured. If someone is sick they breathe in a lot more air. Might breathe out their co2 and be dying. But they would show in his study to have a higher metabolism.

Yes, someone dying breathes in a lot more air. But I don't think they necessarily consume lots more oxygen (not sure about this - Peat has mentioned the age-pigment lipofuscin wasting oxygen).
I don't think the dying person would show high metabolism with this method.

 

[tara]

I don't think the study mentions cortisol or adrenaline. So I guess they did not do anything to distinguish metabolism maintained by stress hormones from metabolism maintained by thyroid hormones?