Ahanu
Member
- Joined
- Sep 13, 2015
- Messages
- 432
If they didnt measure Cortisol, Progesteron etc then it makes no sense to use this Baltimore study as an argument against peat claims. But i am sure this had been said allready a hundred Times.
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Baltimore study said:BMR was [...] expressed as kcal/m2/h, based on DuBois’s equation to estimate the body surface area.
Durnin said:Body weight is the most important factor in modifying BMR but its effect will vary with the age group of the individual.
Durnin said:[...] there are two theoretical considerations which somewhat inhibit the acceptance of surface area as the unit of size. Firstly, as mentioned above, if surface area determines the heat loss from the body, the level of basal metabolism must depend upon the surface area, whereas, in fact, basal metabolism is a function of the metabolic activity (or oxygen consumption) of all the separate active tissues of the body and is dependent on the relative mass of these tissues.
Durnin said:Secondly, surface area is not a reference which is measured. It is calculated from height and weight, probably using the formula of Du Bois & Du Bois (1916), and has an unknown error attached to its use for any given individual [...] Body weight, on the other hand, if it can be shown to be an acceptable reference, is one of the easiest and most accurate of all biological measurements.
Durnin said:Mitchell, Strydom, van Graan & vander Walt (1971) found that the Du Bois formula consistently underestimated the surface area of 237 young adult males relative to the true area as measured by a photometric technique.
These effects work all in the same direction.Mitchell said:[...] the smaller the man, the larger the discrepancy. [source]
The ones who died were older at first visit. They had a higher BMI. Despite their shorter follow-up time they had more visits per participant....Can somebody explain this ? The older people had higher BMR.
:10:Is the entire study not skewed by those age differences?
The people with major adrenal issues where excluded.If they didnt measure Cortisol, Progesteron etc then it makes no sense to use this Baltimore study as an argument against peat claims. But i am sure this had been said allready a hundred Times.
A full read of the paper you quoted from leaves me with a very different conclusion than yours. Expressing metabolic rate is kcal/m2/hour is commonly done and there is no evidence that expressing it in terms of mass is better. I think the paper is saying that it is easier to just use mass as surface area is overkill. Both methods have their pros and cons.Body weight (or fat-free mass) should be used to make BMR comparable. For the same BMR expressed in kcal/kg, the BMR expressed in kcal/m² is estimated higher in shorter men and in those with higher weight.
In this FAO paper the use of the surface area as a unit of size is criticized.
I played a bit with the DuBois equation. I used the simple estimation BMR = 25 x body mass to estimate either the BMR or the BMR (kg). Then I varied the body surface area by changing the height or the weight. Here is the result:
These effects work all in the same direction.
BMR is expressed as energy per unit of body size per unit of time. In the past, these units have frequently been kcal/sq.m. of surface area/hour. Whether or not these are the most appropriate units is a matter for considerable controversy. It should be noted immediately that there is no unanimity on the proper unit for body size
“The conclusion must surely be that, at the present time, there are no means available to us to be precise in our estimate of BMR, other than in a completely spurious manner. It is quite astonishing to consider the probably futile efforts which have been exerted in the examination, of the data on man, of weight, weight to the power 0.7, 0.73 or 0.75, and surface area, as the unit of preference when there is clearly almost no difference between any of them, all of them are useful only in a very imperfect fashion, and one of them - weight - is easy, accurate and simple to measure and to utilize”
IMO he is not saying that utilizing mass is more accurate than using surface area but rather that using surface area, which takes into account both mass and body shape, would be overkill as there is so much other variability in the assessment of energy use. In other words just using the biggest driver of BMR, body weight, is good enough and that more complicated method such as surface area are not justified. This is just one researcher's opinion and others have different opinions.“A table has been formulated to allow prediction of BMR in individuals of any age or of a range of body weights. Body weight is the most important factor in modifying BMR but its effect will vary with the age group of the individual. The use of this table is certainly open to some error but the variability of the published data is such that it is unlikely that more complex methods of calculating BMR offer any increased accuracy and the present table has the great advantage of being very easy to apply.”
I think peat considers the medical classification for thyroid dysfunction not excact. He thinks there are much more people with thyroid dysfunction than recocnised.The people with major adrenal issues where excluded.
“Participants with known or suspected thyroid or adrenal dysfunction, as evidenced by history, drug use, or physical examination, were excluded. “
I would guess that the percentage of people with higher metabolisms and undiagnosed high cortisol is fairly low since most people don’t have chronically jacked cortisol levels over a 40 year period. I don’t think that the small numbers would change the study's conclusions given such a dramatic increase in mortality due to higher metabolism.
true but you typically don't want to do studies on only people in perfect health with all of their numbers in the optimal range. You want to look at the general population and exclude only those with really bad health problems.I think peat considers the medical classification for thyroid dysfunction not excact. He thinks there are much more people with thyroid dysfunction than recocnised.
I think those judges were paid off. Of course the differences in age are taken into account. Otherwise the findings would be “Increased age is a Risk Factor for Mortality.” They measured mortality using “excess mortality.” This is the difference between the expected death rate and the observed death rate. The expected death rates take into account the age of each participant plus many other covariates:Drareg said: ↑" Is the entire study not skewed by those age differences?"
:10:
I think a better question to ask is why Drareg and you are so intent on knocking down every study that contradicts Ray. What if we maintain an open mind, subject all studies to equal scrutiny, and go wherever the evidence leads usModel 1 was adjusted for age, date of visit, race, weight, and BMI. Model 2 was also adjusted for smoking, and Model 3 was adjusted for all covariates of Model 2 plus total physical activity, creatinine excretion, muscle strength, and white blood cell count.
I belive that is what peat is doing. It is just not that simple as some would like it to be.What if we maintain an open mind, subject all studies to equal scrutiny, and go wherever the evidence leads us
@Drareg So you still haven’t found any studies to support your faith based ideology. As for your last rant, I hope you were able to get out some of the frustrations you must be feeling. The sheer amount of anger and scorn coming from you is only matched by your lack of understanding about clinical research. You say I am filled with “deluded hubris fuelled mania” and then proceed to try to tear down one of the most respected and well funded studies on aging in the world. Why don't you post some of your studies so we can all learn how it should be done. Instead of trying to discredit it, you could try to actually learn something from it. Clinical studies rarely get any better than this. Baltimore Longitudinal Study of Aging |
Though you didn't get to use your favorite word "Strawman" until the very end, I am glad you wasted no time in creating yet another Strawman of your own.
This is what I wrote:
See the difference?
I appreciate the time you must have spent combing through the study, searching out potential flaws, typing up carefully considered arguments and thinking up all those multi adjective insults. With that in mind, you can rest assured that I will give your post and all of its many questions all the due consideration that they deserve. now that is priceless
I think peat considers the medical classification for thyroid dysfunction not excact. He thinks there are much more people with thyroid dysfunction than recocnised.
I think those judges were paid off. Of course the differences in age are taken into account. Otherwise the findings would be “Increased age is a Risk Factor for Mortality.” They measured mortality using “excess mortality.” This is the difference between the expected death rate and the observed death rate. The expected death rates take into account the age of each participant plus many other covariates:
I think a better question to ask is why Drareg and you are so intent on knocking down every study that contradicts Ray. What if we maintain an open mind, subject all studies to equal scrutiny, and go wherever the evidence leads us
true but you typically don't want to do studies on only people in perfect health with all of their numbers in the optimal range. You want to look at the general population and exclude only those with really bad health problems.
The ones who died were older at first visit. They had a higher BMI. Despite their shorter follow-up time they had more visits per participant....
:10:
The people with major adrenal issues where excluded.
“Participants with known or suspected thyroid or adrenal dysfunction, as evidenced by history, drug use, or physical examination, were excluded. “
I would guess that the percentage of people with higher metabolisms and undiagnosed high cortisol is fairly low since most people don’t have chronically jacked cortisol levels over a 40 year period. I don’t think that the small numbers would change the study's conclusions given such a dramatic increase in mortality due to higher metabolism.
The ones who died were older at first visit. They had a higher BMI. Despite their shorter follow-up time they had more visits per participant....
:10:
This is how I understand it too.In other words, TSH is useful to understand the gap between where your hypothalamus wants the overall metabolism at and where it actually is. If TSH is high, your hypothalamus wants to raise metabolism from where it currently is, and if it is very low, it wants to decrease metabolism relative to where it currently is. But TSH by itself cannot give much info as to where to metabolism is at relative to a standard.
Indeed. Some of the people with poorer glycogen stores may be more likely to have stress-elevated metabolism in the morning fasted state than some of the healthier ones with stronger stores.Important not to forget the fasting for 12 hours and the effects this would have on mobilising stress hormones.