Racial difference in body core temperature between Pima Indian and Caucasian men.
A low body temperature is associated with a low metabolic rate for a given body size and body composition. These two traits might have been assets in the history of a population subjected to cycles of feast and famine, but became part of an obesity-prone syndrome in our westernized society characterized by plenty of food and a sedentary lifestyle. We tested whether Pima Indians have lower body temperatures than Caucasians, a trait which might partly explain the high prevalence of obesity in this population. Twenty-five Pima Indian (28 +/- 6 yrs, 87.8 +/- 22.8 kg, 29 +/- 9% body fat) and 25 Caucasian (30 +/- 5 yrs, 80.7 +/- 18.4 kg, 22 +/- 11% body fat) men had body core temperatures measured by telemetry for 24 h while in a respiratory chamber. Mean daily body core temperature was 36.93 +/- 0.12 and 36.90 +/- 0.22 degrees C in Pima Indians and Caucasians, respectively. Since body core temperature during sleep (SLBCT) correlated with percentage body fat, a subset of 10 Pima Indians and 10 Caucasians were pair-matched for body weight and percentage body fat. In this group, SLBCT was lower in Pima Indians than in Caucasians (36.45 +/- 0.10 vs 36.65 +/- 0.27 degrees C; P < 0.01) and, ethnic group accounted for 20% of the variance in SLBCT (P < 0.01). Surprisingly, the lower SLBCT was not associated with a low metabolic rate and therefore does not seem to play a role in the etiology of obesity in Pima Indians.(ABSTRACT TRUNCATED AT 250 WORDS)
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Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona 85016, USA.
Fontvieille
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Larson
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Spraul
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Bogardus
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Ravussin
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D000273:Adipose Tissue; D000328:Adult; D001481:Basal Metabolism; D001823:Body Composition; D001831:Body Temperature; D001835:Body Weight; D002940:Circadian Rhythm; D005006:Ethnicity; D006801:Humans; D007198:Indians, North American; D008297:Male; D009765:Obesity / Q000209:etiology; D012890:Sleep; D044465:White People