European Ancestry and Resting Metabolic Rate in Older African Americans

T.M. Manini et al., European Journal of Clinical Nutrition, April 6, 2011

Background/Objectives:

Resting metabolic rate (RMR) contributes 60–80%of total energy expenditure and is consistently lower in populations of African descent compared with populations of European populations. Determination of European ancestry (EA) through single nucleotide polymorphism (SNP) analysis would provide an initial step for identifying genetic associations that contribute to low RMR. We sought to evaluate the association between RMR and EA in African Americans.

Subjects/Methods:

RMR was measured by indirect calorimetry in 141 African American men and women (aged 74.7±3.0 years) enrolled in a substudy of the Health, Aging and Body Composition Study. Ancestry informative markers were used to estimate individual percent EA. Multivariate regression was used to assess the association between RMR and EA after adjustments for soft tissue fat-free mass (STFFM), fat mass, age, study site, physical activity level and sex.

Results:

Mean EA was 23.8±16% (range: 0.1–70.7%) and there were no differences by sex. Following adjustments, each percent EA was associated with a 1.6 kcal/day (95% Confidence interval: 0.42, 2.7 kcal/day) higher RMR (P=0.008). This equates to a 160 kcal/day lower RMR in a population of completely African ancestry, with one of completely European ancestry. Additional adjustment for trunk STFFM that partially accounts for high-metabolic rate organs did not affect this association.

Conclusions:

EA in African Americans is strongly associated with higher RMR. The data suggest that population differences in RMR may be due to genetic variants.

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  • Anonymous

    “Blacks have lower resting metabolic rates than whites. ”

    A lower metabolic rate can be generally tied to the tendency to obesity.

  • Istvan

    Wouldn’t a higher RMR make more body heat and therefore keep a body warmer? In the jungle a body that makes a lot of its own heat wouldn’t be required. In a colder enviroment it makes sense. Kind of like Eskimos are short and stocky to stay warm in a frigid environment.

  • Anonymous

    Wouldn’t a higher RMR make more body heat and therefore keep a body warmer? In the jungle a body that makes a lot of its own heat wouldn’t be required. In a colder enviroment it makes sense. Kind of like Eskimos are short and stocky to stay warm in a frigid environment.

    Makes sense to me. I wonder what the figures are for Asians and Amerindians? We might presume that Asians would have a higher rate, and Amerindians (including mestizo Mexicans) lower.

  • Deirdre

    Yep, we’re all exactly the same. Young black males awakening from anesthesia will beat the life out of you so in addition to being strapped down, two extra people on each side leaning full body weight on them for emergence or else they will be hanging from the OR light. Insanity.

  • SF Paul

    It is just amazing how many biological and chemical differences there are between the races. Science has most likely just scratched the surface on this fascinating subject. Of course the mainstream media will always try to cover up and ignore any facts that do not support the colorblind society of equality.

  • Anonymous

    Thinking and using your brain for study (as an example) requires a lot of food. Scientific studies have indicated that students over eat while they are studying. Students who don’t take in enough food lose weight rapidly.

    Africans are simply not using their brains when they are idle.

  • Ben

    @ 2

    Constant movement is required to stay warm. A byproduct from skeletal muscle tissue contracting is heat. From an evolutionary point of view, our metabolism increased so that cells were more efficient at the metabolic process which was crucial to staying warm in colder environments.

    @ 3

    I would assume so…

  • Anonymous

    Ref. #01 obesity

    **************************

    Perhaps some of their dietary preferences should be catered to more–collard greens, etc? and far less American fast food?

  • elitist

    The most interesting aspects of this story is simply the fact that such research is being conducted and published, thereby demolishing, step-by-step, the myth that there are no important racial differences (or in the wilder and more demented version that is current these days, that there is “no such thing as race”).

    It seems to me, however, that there could be interesting implications for racial differences in intelligence:

    what level of mental activity is associated with RMR in blacks and whites respectively?

    Could a lower level of RMR be associated with mental torpor and intellectual passivity?

  • Matt

    istvan: “Wouldn’t a higher RMR make more body heat and therefore keep a body warmer?”

    elitist: “Could a lower level of RMR be associated with mental torpor and intellectual passivity?”

    I’d guess that a heightened RMR is required to generate warmth in cold climates, and not contrapositively not required in warmer climates. A higher RMR presumably requires greater amounts of food, as a car running fewer MPG requires more gas. Hence, due to both the relative scarcity of food compounded by the need for greater amounts of food, there would be an inherent selection toward those of the species who are able to better a) plan ahead (e.g., store food for winter), b) observe and record (e.g., lunar and solar cycles), and c) advance technology (e.g., improved hunting and farming implements and techniques). I.e., cold climate = lower RMR = great need for resource planning = natural selection for higher IQs.

    Lower RMR allows for longer retention of nutrient-borne energy reserves, allowing for more time between “times of plenty”, lessening the survival advantage of “future time orientation”…and IQ in general.

  • Anonymous

    Previous studies have also shown that blacks have lower metabolic rates because their high-metabolism organs are smaller (liver, kidney, spleen, heart and brain…)

    I don’t know what the difference in liver, kidney, etc are supposed to be, but there is a well known difference in average brain size that accounts for some of the lower metabolic rate (the brain being very expensive energetically).

  • Anonymous

    Dear Post # 4, Deirdre,

    Do you or anyone else have any data, published report, etc. that suggest that post-op violence has a racial component? I’d like to see it.

  • Anonymous

    8 — Anonymous wrote at 12:52 AM on October 7:

    Ref. #01 obesity

    **************************

    Perhaps some of their dietary preferences should be catered to more—collard greens, etc? and far less American fast food?”

    Preferences? Fried chicken and other fatty foods are preferred. In Africa, wherever there is no famine, blacks tend to become obese easily. Tropical climates slow all functions down, from brain activity to physical activity. In temperate zones the body requires more calories just to stay warm at rest. Evolution would necessarily create a physiology that used more energy in order to survive.

    The genetic aspect isn’t the only factor in obesity, but it is a significant part of it. For example, when people are subjected to poverty (or a stressor producing similar mental stress), they tend to crave more fatty foods. This is because their psychological stress is acting to prepare them for famine (bad times)and it becomes a chronic mental condition. Poor people are less happy and tend to not exercise as much, let along “recreate.” When one starves the body, the response when food again becomes available is to pack on fat first, rather than build muscle up (unless you rehabilitate the patient with exercise to prevent it).

    The bodies own intelligence (homeostatic regulation) often does things that may not be desirable in some other aspects like the longer term development of heart and vascular disease, but corrects for extremes with extremes. Of course available food has a lot to do with it as well.

  • john

    This is impossible. “Everbody knows” that blacks are identical in all respects to whites. Any purported differences are due entirely to racist attitudes by whites.

    I’m surprised to see such an article in AR.

  • Anonymous

    Ref. 05

    Good observation. The late Glayde Whitney made the point at an

    AR presentation years ago that our times are unprecedented in the extent to which there are discoveries made in a wide range of disciplines that are “dynamite” as soon as their inter-relationships are perceived and given test. A final line of battle of the forces of the big lie Blank Slate dogma will be to keep such facts in isolation.