Modeling the Epidemiologic Transition Study
| Status: | Active, not recruiting |
|---|---|
| Conditions: | Obesity Weight Loss |
| Therapuetic Areas: | Endocrinology |
| Healthy: | No |
| Age Range: | 18 - 50 |
| Updated: | 8/4/2018 |
| Start Date: | July 2008 |
| End Date: | December 2020 |
This project examines whether individuals' amount of activity energy expenditure (AEE) is
related to adiposity and adiposity/diabetes-related hormones in a diverse sample of 2500, and
to test the ecological hypothesis that a decline in levels of AEE is an important cause of
the increases in obesity that are currently taking place in many societies.
One goal is to use doubly labeled water and/or accelerometers to objectively measure activity
energy expenditure in community samples from five adult populations across the spectrum of
obesity risk. From each site, (i.e., Ghana, South Africa, Seychelles, Jamaica, and the US),
500 black adults will be recruited. Among all participants, AEE will be measured using
accelerometers and in a subset of 75 per site, AEE will also be measured by doubly labeled
water.
The doubly labeled water sample will be used to confirm site-specific concordance with the
accelerometer measurements and to estimate population mean levels of AEE. Additionally, body
composition, dietary intake, fasting glucose, insulin, adiponectin, leptin and ghrelin will
be measured. The relationships between calories expended in activity and body composition,
dietary intake, glucose, hormones and adipocytokines, both within and between each population
using doubly labeled water and accelerometers will be examined. In this longitudinal study,
weight will be measured at 12 and 24-months, and AEE by accelerometer will be assessed at
enrollment and again at 2-years of follow-up; associations between change in AEE and change
in weight will be estimated.
The central purpose of this project is to test whether AEE or change in AEE can be identified
as a contributory mechanism to population-wide weight gain and, if so, to quantify its
importance. In addition, we seek to understand the interrelationships between the
adipocytokines and the hormones ghrelin and insulin as well as AEE in the regulation of body
weight across the continuum of body mass indices (BMI) represented by these five populations.
related to adiposity and adiposity/diabetes-related hormones in a diverse sample of 2500, and
to test the ecological hypothesis that a decline in levels of AEE is an important cause of
the increases in obesity that are currently taking place in many societies.
One goal is to use doubly labeled water and/or accelerometers to objectively measure activity
energy expenditure in community samples from five adult populations across the spectrum of
obesity risk. From each site, (i.e., Ghana, South Africa, Seychelles, Jamaica, and the US),
500 black adults will be recruited. Among all participants, AEE will be measured using
accelerometers and in a subset of 75 per site, AEE will also be measured by doubly labeled
water.
The doubly labeled water sample will be used to confirm site-specific concordance with the
accelerometer measurements and to estimate population mean levels of AEE. Additionally, body
composition, dietary intake, fasting glucose, insulin, adiponectin, leptin and ghrelin will
be measured. The relationships between calories expended in activity and body composition,
dietary intake, glucose, hormones and adipocytokines, both within and between each population
using doubly labeled water and accelerometers will be examined. In this longitudinal study,
weight will be measured at 12 and 24-months, and AEE by accelerometer will be assessed at
enrollment and again at 2-years of follow-up; associations between change in AEE and change
in weight will be estimated.
The central purpose of this project is to test whether AEE or change in AEE can be identified
as a contributory mechanism to population-wide weight gain and, if so, to quantify its
importance. In addition, we seek to understand the interrelationships between the
adipocytokines and the hormones ghrelin and insulin as well as AEE in the regulation of body
weight across the continuum of body mass indices (BMI) represented by these five populations.
Populations all over the world are experiencing rapid increases in the prevalence of obesity
and diabetes. To date, the public health response to the emerging obesity epidemic has been
almost totally ineffective. As a first line of response, professional bodies and government
organizations have issued prevention guidelines, all of which include recommendations on
levels of activity energy expenditure (AEE). However, even if fully implemented, it is not
clear that the current recommendations on AEE would impact the trend in age-related weight
gain. In fact, there is virtually no direct evidence that can be brought to bear on the
question of whether the obesity epidemic has resulted primarily or even partially from
society-wide declines in habitual physical activity (PA).
To date, epidemiologic research on AEE has relied on very crude measurement tools—primarily
questionnaires. These self-reported data capture only a small fraction of the total variance
in activity and are potentially confounded when they focus on leisure-time PA. By contrast,
direct measurement with doubly labeled water (DLW) provides a precise, unbiased estimate of
all forms of non-resting energy expenditure. DLW has also been used to validate the new
generation of accelerometers which are efficient measurement tools for larger studies.
In this study, objective measurement tools will be used to examine the "ecology of AEE". This
study will take place in 5 countries spanning the range of the activity-obesity spectrum and
will combine both within-population person-level and between-population ecological analyses.
First, the study will examine whether an individual's amount or pattern of AEE is related to
adiposity in a diverse sample of 2,500. Second, the study will evaluate whether a decline in
levels of AEE is an important cause of the rapid increases in obesity that currently take
place in many societies. As an exploratory aim we will examine the role of selected
adipocytokines and the appetite hormone ghrelin.
and diabetes. To date, the public health response to the emerging obesity epidemic has been
almost totally ineffective. As a first line of response, professional bodies and government
organizations have issued prevention guidelines, all of which include recommendations on
levels of activity energy expenditure (AEE). However, even if fully implemented, it is not
clear that the current recommendations on AEE would impact the trend in age-related weight
gain. In fact, there is virtually no direct evidence that can be brought to bear on the
question of whether the obesity epidemic has resulted primarily or even partially from
society-wide declines in habitual physical activity (PA).
To date, epidemiologic research on AEE has relied on very crude measurement tools—primarily
questionnaires. These self-reported data capture only a small fraction of the total variance
in activity and are potentially confounded when they focus on leisure-time PA. By contrast,
direct measurement with doubly labeled water (DLW) provides a precise, unbiased estimate of
all forms of non-resting energy expenditure. DLW has also been used to validate the new
generation of accelerometers which are efficient measurement tools for larger studies.
In this study, objective measurement tools will be used to examine the "ecology of AEE". This
study will take place in 5 countries spanning the range of the activity-obesity spectrum and
will combine both within-population person-level and between-population ecological analyses.
First, the study will examine whether an individual's amount or pattern of AEE is related to
adiposity in a diverse sample of 2,500. Second, the study will evaluate whether a decline in
levels of AEE is an important cause of the rapid increases in obesity that currently take
place in many societies. As an exploratory aim we will examine the role of selected
adipocytokines and the appetite hormone ghrelin.
Inclusion Criteria:
- Identify as African American or Black
- Age 18-50
Exclusion Criteria:
- Pregnancy, nursing, or planning to become pregnant
- Movement disorders or other disability that limits mobility
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