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Metabolic rate and body composition of Pima Indian and Caucasian children
1Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, AZ 85016.
Insights
Pima Indian children do not have a low resting metabolic rate (RMR). Weight gain in these children is likely due to reduced physical activity or excess calorie intake, not a slow metabolism.
Area of Science:
- Human Physiology
- Pediatric Obesity Research
- Metabolic Studies
Background:
- Obesity prevalence exceeds 75% in the Pima Indian population.
- A low resting metabolic rate (RMR) may be a risk factor for weight gain.
- Previous research suggests potential metabolic differences in Pima Indian children.
Purpose of the Study:
- To investigate if Pima Indian children exhibit a lower RMR compared to Caucasian children.
- To explore the relationship between RMR, body composition, and weight gain in pediatric populations.
Main Methods:
- Measured body composition (bioelectrical resistance) and RMR in Pima Indian and Caucasian children.
- Compared absolute and adjusted RMR values between the two groups, accounting for body size, composition, and sex.
- Analyzed correlations between adjusted RMR and parental BMI in prepubescent Pima Indian girls.
Main Results:
- Pima Indian children were significantly taller, heavier, and had higher body fat percentages than Caucasian children.
- Absolute RMR was higher in Pima children, but adjusted RMR values were similar between groups.
- In prepubescent Pima girls, adjusted RMR negatively correlated with parental BMI.
Conclusions:
- Pima Indian children do not present with a low resting metabolic rate.
- Factors such as reduced physical activity or excess energy intake are likely primary drivers of weight gain in 10-year-old Pima children.
- The potential role of a low metabolic rate as a predisposing factor in earlier childhood remains a possibility.
Abstract:
A low metabolic rate for a given body size and body composition may be a risk factor for body weight gain. Because the prevalence of obesity exceeds 75% in the Pima Indian population, we investigated whether Pima Indian children have a low resting metabolic rate (RMR) when compared with Caucasian children. Body composition (bioelectrical resistance) and RMR were measured in 43 Pima Indian children (22 male/21 female, means +/- SD = 9.9 +/- 1.1 year) and 42 Caucasian children (21 male/21 female, 9.7 +/- 1.2 year). Pima Indian children were taller (p < 0.001), heavier (p < 0.001), and fatter (p < 0.0001) than Caucasian children. Absolute values of RMR were higher in the Pimas than in the Caucasians (p < 0.001), but were similar when adjusted for differences in body size, body composition, and sex. In Pima Indian girls before puberty (< 10 years; n = 8), adjusted values of RMR were negatively correlated with the mean body mass index (BMI) of the parents (r = -0.88; p < 0.005). Inasmuch as resting metabolic rate was not low in Pima children, the data suggest that the major factors in the weight gain of 10-year-old Pima children may be reduced physical activity and/or excess energy intake. However, this study does not exclude the possibility that a low metabolic rate may be a predisposing factor at an earlier age.