Protocol for the modeling the epidemiologic transition study: a longitudinal observational study of energy balance and change in body weight, diabetes and cardiovascular disease risk

Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA.
BMC Public Health (Impact Factor: 2.32). 12/2011; 11:927. DOI: 10.1186/1471-2458-11-927
Source: PubMed

ABSTRACT The prevalence of obesity has increased in societies of all socio-cultural backgrounds. To date, guidelines set forward to prevent obesity have universally emphasized optimal levels of physical activity. However there are few empirical data to support the assertion that low levels of energy expenditure in activity is a causal factor in the current obesity epidemic are very limited.
The Modeling the Epidemiologic Transition Study (METS) is a cohort study designed to assess the association between physical activity levels and relative weight, weight gain and diabetes and cardiovascular disease risk in five population-based samples at different stages of economic development. Twenty-five hundred young adults, ages 25-45, were enrolled in the study; 500 from sites in Ghana, South Africa, Seychelles, Jamaica and the United States. At baseline, physical activity levels were assessed using accelerometry and a questionnaire in all participants and by doubly labeled water in a subsample of 75 per site. We assessed dietary intake using two separate 24-hour recalls, body composition using bioelectrical impedance analysis, and health history, social and economic indicators by questionnaire. Blood pressure was measured and blood samples collected for measurement of lipids, glucose, insulin and adipokines. Full examination including physical activity using accelerometry, anthropometric data and fasting glucose will take place at 12 and 24 months. The distribution of the main variables and the associations between physical activity, independent of energy intake, glucose metabolism and anthropometric measures will be assessed using cross-section and longitudinal analysis within and between sites.
METS will provide insight on the relative contribution of physical activity and diet to excess weight, age-related weight gain and incident glucose impairment in five populations' samples of young adults at different stages of economic development. These data should be useful for the development of empirically-based public health policy aimed at the prevention of obesity and associated chronic diseases.

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    ABSTRACT: The aim of this study was to compare physical activity measured using GT1M ActiGraph and GT3X ActiGraph accelerometers in free living conditions. Twenty-five adults wore GT1M and GT3X Actigraph accelerometers simultaneously during a typical weekday of activity. Data were uploaded from the monitor to a computer at the end of test (one day). Previously established thresholds were used for defining time spent at each level of physical activity, physical activity was assessed at varying intensities comparing data from the two accelerometers by ANOVA and Bland and Altman statistical analysis. The concordance correlation coefficient between accelerometers at each intensity level was 0.99. There were no significant differences between accelerometers at any of the activity levels. Differences between data obtained in minutes with the GT1M accelerometer and the GT3X monitor were to 0.56, 0.36, 0.52 and 0.44% for sedentary, light, moderate and vigorous, respectively. The Bland and Altman method showed good agreement between data obtained for the two accelerometers. Findings suggest that the two accelerometers provided similar results and therefore the GT3X may be used in clinical and epidemiological studies without additional calibration or validation studies.
    BMC Research Notes 04/2012; 5:187. DOI:10.1186/1756-0500-5-187
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    ABSTRACT: Background/objectives:There is little objective information regarding nutrition transition in African countries. We assessed trends in nutrition patterns in the Seychelles between 1989 and 2011.Subjects/Methods:Population-based samples were obtained in 1989, 1994 and 2011 and participants aged 25-44 are considered in this study (n=493, 599 and 471, respectively). Similar, although not identical, food frequency questionnaires (FFQs) were used in each survey and the variables were collapsed into homogenous categories for the purpose of this study.Results:Between 1989 and 2011, consumption frequency of fish (5+/week) decreased from 93 to 74%, whereas the following increased: meat (5+/week) 25 to 51%, fruits (1+/week) 48 to 94%, salty snacks (1+/week) 22 to 64% and sweet snacks (1+/week) 38 to 67% (P<0.001 for all). Consumption frequency decreased for home-brewed alcoholic drinks (1+/week) 16 to 1%, but increased for wine (1+/week) 5 to 33% (both P<0.001). Between 2004 and 2011, consumption frequency decreased for rice (2/day) 62 to 57% and tea (1+/day) 72 to 68%, increased for poultry (1+/week) 86 to 96% (all P<0.01), and did not change for vegetables (70.3 to 69.8%, P=0.65).Conclusions:Seychelles is experiencing nutrition transition characterized by a decreased consumption frequency of traditional staple foods (fish, polished rice), beverages (tea) and of inexpensive home brews, and increased consumption frequency of meat, poultry and snacks. Food patterns also became more varied along with a broader availability of products in the 22-year interval. The health impact of these changes should be further studied.European Journal of Clinical Nutrition advance online publication, 19 December 2012; doi:10.1038/ejcn.2012.199.
    European journal of clinical nutrition 12/2012; 67(2). DOI:10.1038/ejcn.2012.199 · 2.95 Impact Factor
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    ABSTRACT: Background/Objectives Bio-electrical impedance analysis (BIA) is used in population and clinical studies as a technique for estimating body composition. Because of significant underrepresentation in existing literature, we sought to develop and validate predictive equation(s) for BIA for studies in populations of African origin. Subjects/Methods Among five cohorts of the Modeling the Epidemiologic Transition Study (METS), height, weight, waist circumference and body composition, using isotope dilution, were measured in 362 adults, ages 25 to 45 with mean BMIs ranging from 24 to 32. BIA measures of resistance and reactance were measured using tetrapolar placement of electrodes and the same model of analyzer across sites (BIA 101Q, RJL Systems). Multiple linear regression analysis was used to develop equations for predicting FFM, as measured by isotope dilution; covariates included sex, age, waist, reactance and height2/resistance, along with dummy variables for each site. Developed equations were then tested in a validation sample; FFM predicted by previously published equations were tested in the total sample. Results A site-combined equation and site-specific equations were developed. The mean differences between FFM (reference) and FFM predicted by the study-derived equations were between 0.4–0.6 kg (i.e. 1% difference between actual and predicted FFM) and the measured and predicted values were highly correlated. The site-combined equation performed slightly better than the site-specific equations and the previously published equations. Conclusions Relatively small differences exist between BIA equations to estimate FFM, whether study-derived or published equations, although the site-combined equation performed slightly better than other. The study-derived equations provide an important tool for research in these understudied populations.
    European journal of clinical nutrition 07/2013; 67(9). DOI:10.1038/ejcn.2013.123 · 2.95 Impact Factor
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