Author
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YAO, MANJIANG - TUFTS-HNRCA |
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MCCROY, MEGAN - TUFTS-HNRCA |
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MA, GUANSHENG - INST OF NUTRI & FOOD HYGN |
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TUCKER, KATHERINE - TUFTS-HNRCA |
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GAO, SHUJUN - INST OF NUTRI & FOOD HYGN |
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FUSS, PAUL - TUFTS-HNRCA |
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ROBERTS, SUSAN - TUFTS-HNRCA |
Submitted to: The American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/18/2002 Publication Date: 6/1/2003 Citation: YAO, M., MCCROY, M.A., MA, G., TUCKER, K.L., GAO, S., FUSS, P., ROBERTS, S.B. RELATIVE INFLUENCE OF DIET AND PHYSICAL ACTIVITY ON BODY COMPOSITION IN URBAN CHINESE ADULTS. AMERICAN JOURNAL OF CLINICAL NUTRITION. 2003;77:1409-16. Interpretive Summary: The prevalence of overweight and obesity continues to increase nationally and worldwide. Consumption of a Western-style diet and low levels of physical activity have been widely implicated as underlying causes of the worldwide trend for weight gain. However, there remains controversy over which specific dietary factors are the most important determinants of body fatness. Furthermore, relatively little work has examined the contributions of diet and physical activity to body fatness. The purpose of this study was to investigate the cross sectional associations of dietary variables and physical activity with body fatness by using validated methods for measuring all primary variables. We conducted the study in China, and we anticipated the data could be contrasted with related data emerging from Western countries to further elucidate the roles of diet and physical activity in energy regulation. The subjects were 130 adults living in urban areas of Beijing. Those persons who were aged 35-39 years were given a screening test, which included a screening questionnaire by interview, physical examination, and the drawing of blood to test for hemoglobin concentration. The study was conducted over a 9-d period. The subjects were studied in groups of 8-10 and were equally selected from 4 different lifestyle combinations during different study months. The major finding of this study in urban Chinese adults was that dietary variety and the frequency of consumption of restaurant food were positively associated with body fatness, but that dietary fat percentage and energy density were not significantly associated with body fatness. Using validated methods for assessing dietary intake and physical activity in an urban Chinese population, we found that great dietary variety and high frequency of consumption of restaurants meals were predictors of body fatness, but energy density predicted within subject variability in energy intake. These findings highlight the potential importance of dietary variety and frequency of consumption of restaurant meals in influencing dietary intake and body fatness. Additional research using longitudinal study designs is needed to examine further the role of different dietary variables in energy regulation. Technical Abstract: The relative influence of diet and physical activity on body fatness remains uncertain. The objective of the study was to investigate associations of dietary variables and physical activity with body fatness in urban Chinese adults. We conducted a cross-sectional study in 130 weight-stable men and women aged 35-49 y. Subjects were selected from upper and lower tertiles of dietary fat and physical activity on the basis of screening questionnaires. Dietary intake was assessed by weighed food intake, physical activity level (PAL) was calculated as the ratio of predicted total energy expenditure (TEE) to predicted resting energy expenditure, and body composition was measured with the use of (2)H(2)O. Reported energy intake and predicted TEE were validated against TEE determined with the use of (2)H(2)(18)O (n = 73). Body fatness was positively associated with dietary variety (ie, variety of ingredients) (partial r = 0.186, P = 0.039) and frequency of consuming restaurant foods (partial r = 0.237, P = 0.001) and negatively associated with PAL (partial r = -0.307, P = 0.001) in a multiple regression analysis that controlled for sex and confounders. The combined variance accounted for by dietary variety and restaurant food consumption (9.1%) was equivalent to that for PAL (9.4%). Neither dietary fat nor energy density predicted body fatness, but dietary energy density predicted within-subject day-to-day variation in reported energy intake (P < 0.001). Dietary variety, frequency of restaurant food consumption, and PAL significantly predicted body fatness in urban Chinese adults, but dietary fat did not. These findings support previous studies in US adults and suggest that dietary variables other than fat have an important influence on adult body composition. |