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  #1  
Unread 02-29-2008, 10:52 PM
Balldez Balldez is offline
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Default A metabolism question

How much can a BMR vary in calories per day between individuals of the same gender and weight? I have read that is is plus or minus 35 calories per day. I am looking for studies to confirm or refute that.
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  #2  
Unread 03-01-2008, 01:16 AM
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lylemcd lylemcd is offline
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there's about a +- 15% variance from the highest responder to the lowest. So for a givne weight, if the predicted value was 2000 calories, you might see range of 1850 to 2150 or something like that between the highest and lowest responders

get one of these
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Curr Opin Clin Nutr Metab Care. 2004 Nov;7(6):599-605. Links
Variability in energy expenditure and its components.

Donahoo WT, Levine JA, Melanson EL.
Department of Medicine, Section of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont, USA.
PURPOSE OF REVIEW: To review factors contributing to variation in total daily energy expenditure and its primary components: (1) resting metabolic rate; (2) diet-induced thermogenesis; and (3) activity thermogenesis, including exercise energy expenditure and nonexercise activity. For each component, the expected magnitude of intra-individual variability is also considered. We also reviewed studies that quantified the variability in 24 h energy expenditure. RECENT FINDINGS: In humans, the coefficient of variation in the components of total daily energy expenditure is around 5-8% for resting metabolic rate, 1-2% for exercise energy expenditure, and around 20% for diet-induced thermogenesis. The coefficient of variance for 24 h energy expenditure measured using a room calorimeter for resting metabolic rate is around 5-10%. Thus, these measures are all rather reproducible. Total daily energy expenditure varies several-fold in humans, not due to variation in resting metabolic rate, diet-induced thermogenesis, or exercise thermogenesis, but rather, due to variations in nonexercise activity. A variety of factors impact nonexercise activity, including occupation, environment, education, genetics, age, gender, and body composition, but little is known about the magnitude of effect. SUMMARY: Resting metabolic rate, diet-induced thermogenesis, exercise energy expenditure, and 24 h energy expenditure are highly reproducible. Coefficient of variation is smallest for exercise energy expenditure, followed by resting metabolic rate, 24 h energy expenditure, and diet-induced thermogenesis. There is considerable variability in total daily energy expenditure, largely due to variations in nonexercise activity. Although the factors that impact upon nonexercise activity are understood, their contribution to variation in total daily energy expenditure is unclear.
***
Obes Res. 1995 Mar;3 Suppl 1:59-66.Links
Variation in total energy expenditure in humans.

Goran MI.
Department of Nutrition Sciences, University of Alabama, Birmingham 35294, USA.
The purpose of this paper is to review current data regarding the factors contributing to variability in total energy expenditure (TEE) among humans. Variation arising from within and between individuals and between study groups will be considered. For within- subject variation, issues relating to experimental and theoretical measurement error will be considered in addition to inherent physiological variation. The literature reporting TEE in various study groups is reviewed, highlighting deficiencies in current comparison methods, and a framework by which TEE can be compared between studies and populations is suggested. For between-subject variation, the effects of differences in body composition, obesity, age and gender upon variation in TEE are examined. Finally, data will be reviewed relating to changes in TEE in response to external manipulation (e.g., activity, overfeeding, stress).
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Unread 03-01-2008, 12:20 PM
Balldez Balldez is offline
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Thank you for your response. I am still a bit confused.

You said "there's about a +- 15% variance from the highest responder to the lowest. So for a givne weight, if the predicted value was 2000 calories, you might see range of 1850 to 2150 or something like that between the highest and lowest responders"

It has been my understand that the most a BMR can vary among individuals of the same weight, gender and age the average variance is about 35 calories per day.

Using a metabolic calculator I found the BMR for women weighing pounds to be:

Age 20 = 1469
Age 30 = 1454
Age 40 = 1425
Age 50 = 1396

It would seem that there would be little variance in individuals of the same age, gender and weight because They all need to maintain body temperature, digest food, repair tissue, breath and have bearing heart. I would think that in the case of the the poorly conditioned 150 lb female that her BMR may be slightly higher because her heart and lungs would need to work harder to overcome higher blood pressure and smaller veins, capillaries and arteries.

I would also think that the TEE of an out of shape person doing the same activities would be the same or slightly higher than the TEE of a fit person due to less PHA and less efficient circulation.
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  #4  
Unread 03-01-2008, 03:11 PM
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lylemcd lylemcd is offline
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there is variance in every aspect of human biology, why would BMR be any different? the 35 value is bogus, where did you derive that from?

differences in levels and sensitivity to thyroid, insulin, leptin, etc impact on this and, as stated, for the same age, gender and bodyweight, BMR can vary something like +-15% total from the predicted average

case in point, studies show that morning temperature is a good indicator of basal metabolic rate, for every degree below a normal of 97-8-98.2, BMR will be reduced by 10%

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Am J Physiol. 1992 Oct;263(4 Pt 1):E730-4. Links
Concomitant interindividual variation in body temperature and metabolic rate.

Rising R, Keys A, Ravussin E, Bogardus C.
Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona 85016.
There is significant variation in metabolic rate in humans, independent of differences in body size, body composition, age, and gender. Although it has been generally held that the normal human "set-point" body temperature is 37 degrees C, these interindividual variations in metabolic rate also suggest possible variations in body temperature. To examine the possibility of correlations between metabolic rate and body temperature, triplicate measurements of oral temperatures were made before and after measurement of 24-h energy expenditure in a respiratory chamber in 23 Pima Indian men. Fasting oral temperatures varied more between individuals than can be attributed to methodological errors or intraindividual variation. Oral temperatures correlated with sleeping (r = 0.80, P < 0.0001), and 24-h (r = 0.48, P < 0.02) metabolic rates adjusted for differences in body size, body composition, and age. Similarly, in the 32 Caucasian men of the Minnesota Semi-Starvation Study, oral temperature correlated with adjusted metabolic rate, and the interindividual differences in body temperature were maintained throughout semistarvation and refeeding. These results suggest that a low body temperature and a low metabolic rate might be two signs of an obesity-prone syndrome in humans.
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  #5  
Unread 03-01-2008, 03:25 PM
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for example, say that you and I are both 35 year old male weighing 180 lbs. Our predicted BMR should be about 11 cal/lb or 1980 calories

say I'm slightly hypothyroid, you're slightly hyperthyroid. within the normal range but I'm low normal and you're high normal. say my morning temp is 97.5 and yours is 98.5. Our actual BMR will be abou 10% different with mine being lower than the predicted normal and yours slightly higher

make sense?
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Unread 03-01-2008, 08:14 PM
Balldez Balldez is offline
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Quote:
Originally Posted by lylemcd View Post
for example, say that you and I are both 35 year old male weighing 180 lbs. Our predicted BMR should be about 11 cal/lb or 1980 calories

say I'm slightly hypothyroid, you're slightly hyperthyroid. within the normal range but I'm low normal and you're high normal. say my morning temp is 97.5 and yours is 98.5. Our actual BMR will be abou 10% different with mine being lower than the predicted normal and yours slightly higher

make sense?
Actually, it doesn't. A body temperature difference of 1 degree F cannot account for a minus 10% TEE in ones BMR. Body temperature is only one component of energy expenditure in the BMR. Let's say that one degree F accounts for 10% reduction in caloric requirement. If we were to reduce the body temperature of livestock from 104 F to 94F and keep them perfectly still we could reduce their feed by 100%. If we were to reduce their body temp to 93 degrees they would then produce energy? One degree is about 1% of body temperature and BMR is the aggregate of body temperature, catabolism, heart beat and respiration.

I am looking for a large study using various forms of calorimetry that tests people of the same age, gender and weight. 35 calories sounds reasonable to me.

Also a 1 less degree F the difference in BTU/calories would be negligible. 1 Calorie is equal to 3.968 Btu. That would be like saying lowering a room thermostat 1 degree would reduce your fuel consumption by 10%.
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Unread 03-01-2008, 08:48 PM
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why are you bothering to ask me the question when you already clearly have the answer? or do you just not understand what I'm talking aout regardging the relationship between body temperature and metabolic rate

the 1 degree = ~10% BMR is very well established as anyone with either hypo or hypertyhroid will happily tell you. or as anyone who has dieted (dieting lowers body temperatature which is indicative of falling BMR).

it matters not what SOUNDS RIGHT to you as physiology is not decided by committeem, logic or intuition. I've given you several studies, you just keep repating the same thing as if sheer repetition will magically make it true

and there is a study with the data you want, completely supporting every word I've said (e.g. showing a couple hundred calorie variacne in BMR from the highest to lowest responder for individuals at any given weight). But I can't find it right now
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Unread 03-01-2008, 08:51 PM
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and you culdn'd drop the temp of your lifestock by 10 degrees to do anything, they'd be dead. so it's a silly comparison

also, it's not that cooling them reduces metabolic rate

a reduction in metabolic rate lowers body temperature

you seem to have reversed cause and effect

do you understand the distinction?
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Unread 03-01-2008, 08:56 PM
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this is the paper you want to get the full text of, it has a lovely graph chartin BMR vs. weight for 916 subjects and clearly shows what I'm taking about

***
Int J Obes Relat Metab Disord. 1999 Jul;23(7):715-22.Links
Determinants of energy expenditure and fuel utilization in man: effects of body composition, age, sex, ethnicity and glucose tolerance in 916 subjects.

Weyer C, Snitker S, Rising R, Bogardus C, Ravussin E.
Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, AZ 85016, USA. cweyer@phx.niddk.nih.gov
BACKGROUND: 24-h energy expenditure (24-EE) and 24-h respiratory quotient (24-RQ) are important measurements in obesity research, but their accurate assessment is limited to few specialized laboratories. OBJECTIVES: 1) To provide comprehensive prediction equations for 24-EE, sleeping metabolic rate (SMR) and 24-RQ, based on a large number of Caucasian and Pima Indian subjects, covering a wide range of body weight and composition, body fat distribution, and age and 2) to test whether Pima Indians have lower metabolic rate and/or higher 24-RQ than Caucasians. SUBJECTS AND METHODS: 916 non-diabetic subjects, aged 31.5 +/- 11.9 y, body weight 90.5 +/- 26.1 kg (mean +/- s.d.), (561 males, 355 females; 416 Caucasians, 500 Pima Indians; 720 with normal (NGT) and 196 with impaired (IGT) glucose tolerance) spent 24 h in a respiratory chamber for measurements of 24-EE, SMR and 24-RQ. Fat-free mass (FFM) and fat mass (FM) were assessed by either hydrodensitometry or DEXA. Waist circumference and waist-to-thigh ratio (WTR) were determined as measures of body fat distribution. RESULTS: In a stepwise multiple regression analysis, FFM, FM, sex, age, WTR, and ethnicity were significant independent determinants of 24-EE (2258 +/- 422 kcal/d), explaining 85% of its variability (24-EE (kcal/d)=696 + 18.9 FFM (kg) + 10.O FM (kg) + 180 male -1.9 age (y) + 7.1 WTR (per decimal) + 44 Pima Indian). SMR (1623 +/- 315kcal/d) was determined (78% of variability) by FFM, FM, sex, age, WTR, and glucose tolerance (SMR (kcal/d) = 443 +/- 14.6 FFM (kg) + 6.9 FM (kg) + 79 male - 1.0 age (y) + 5.8 WTR (per decimal) + 38 IGT), but not by ethnicity. Adjustment for the respective variables reduced the variance in 24-EE from 422 to 162 kcal/d and in SMR from 315 to 146kcal/d. 24-RQ (0.854 +/- 0.026) was determined by waist circumference and energy balance (24-RQ = 0.88429-0.00175 waist circumference (cm) + 0.00004 energy balance (%)), but not by sex, ethnicity or glucose tolerance. With this equation only 13% of the variability in 24-RQ could be explained (residual variance 0.024). Compared to Caucasians, Pima Indians had higher 24-EE, but similar SMR and 24-RQ. CONCLUSIONS: This analysis provides comprehensive prediction equations for 24-EE, SMR and 24-RQ from their major known determinants. It confirms the previous findings that, even after adjustment for body composition, age, sex, ethnicity, and glucose tolerance, there is still considerable variability in energy expenditure and substrate oxidation that may, in part, be genetically determined. In adult Pima Indians, we found no evidence for lower metabolic rate or impaired fat oxidation that could explain the propensity towards obesity in this ethnic group.
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  #10  
Unread 03-01-2008, 10:05 PM
Balldez Balldez is offline
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Quote:
Originally Posted by lylemcd View Post
why are you bothering to ask me the question when you already clearly have the answer? or do you just not understand what I'm talking aout regardging the relationship between body temperature and metabolic rate

the 1 degree = ~10% BMR is very well established as anyone with either hypo or hypertyhroid will happily tell you. or as anyone who has dieted (dieting lowers body temperatature which is indicative of falling BMR).

it matters not what SOUNDS RIGHT to you as physiology is not decided by committeem, logic or intuition. I've given you several studies, you just keep repating the same thing as if sheer repetition will magically make it true

and there is a study with the data you want, completely supporting every word I've said (e.g. showing a couple hundred calorie variacne in BMR from the highest to lowest responder for individuals at any given weight). But I can't find it right now
I don't think the subjective opinion of someone who claims to suffer from hypothyroidism is credible. I am looking for test data done using scientific methods.

Being that body temperature is a percentage of BMR a 1 degree F drop in body temperature cannot reduce caloric expenditure by 10%. Can you show me one study that clearly states that a 1 degree drop in body temp can lower a persons calorie expenditure in BMR by 10%
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